<?xml version="1.0" encoding="US-ASCII"?>
<!--XBRL Document Created with Wdesk from Workiva-->
<!-- -->
<link:linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <link:roleRef roleURI="http://www.boozallen.com/role/AccountsPayableAndOtherAccruedExpenses" xlink:href="bah-20190331.xsd#AccountsPayableAndOtherAccruedExpenses" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AccountsPayableAndOtherAccruedExpensesDetails" xlink:href="bah-20190331.xsd#AccountsPayableAndOtherAccruedExpensesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AccountsPayableAndOtherAccruedExpensesTables" xlink:href="bah-20190331.xsd#AccountsPayableAndOtherAccruedExpensesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AccountsReceivableNetOfAllowance" xlink:href="bah-20190331.xsd#AccountsReceivableNetOfAllowance" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AccountsReceivableNetOfAllowanceDetails" xlink:href="bah-20190331.xsd#AccountsReceivableNetOfAllowanceDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AccountsReceivableNetOfAllowanceTables" xlink:href="bah-20190331.xsd#AccountsReceivableNetOfAllowanceTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AccruedCompensationAndBenefits" xlink:href="bah-20190331.xsd#AccruedCompensationAndBenefits" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AccruedCompensationAndBenefitsDetails" xlink:href="bah-20190331.xsd#AccruedCompensationAndBenefitsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AccruedCompensationAndBenefitsTables" xlink:href="bah-20190331.xsd#AccruedCompensationAndBenefitsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AccumulatedOtherComprehensiveLoss" xlink:href="bah-20190331.xsd#AccumulatedOtherComprehensiveLoss" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AccumulatedOtherComprehensiveLossScheduleOfChangesInAccumulatedOtherComprehensiveIncomeLossDetails" xlink:href="bah-20190331.xsd#AccumulatedOtherComprehensiveLossScheduleOfChangesInAccumulatedOtherComprehensiveIncomeLossDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AccumulatedOtherComprehensiveLossScheduleOfReclassificationsOutOfAccumulatedOtherComprehensiveLossToNetIncomeDetails" xlink:href="bah-20190331.xsd#AccumulatedOtherComprehensiveLossScheduleOfReclassificationsOutOfAccumulatedOtherComprehensiveLossToNetIncomeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AccumulatedOtherComprehensiveLossTables" xlink:href="bah-20190331.xsd#AccumulatedOtherComprehensiveLossTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/Acquisitions" xlink:href="bah-20190331.xsd#Acquisitions" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AcquisitionsNarrativeDetails" xlink:href="bah-20190331.xsd#AcquisitionsNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AcquisitionsScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedDetails" xlink:href="bah-20190331.xsd#AcquisitionsScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AcquisitionsTables" xlink:href="bah-20190331.xsd#AcquisitionsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/BusinessOverview" xlink:href="bah-20190331.xsd#BusinessOverview" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/BusinessOverviewDetails" xlink:href="bah-20190331.xsd#BusinessOverviewDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/BusinessSegmentInformation" xlink:href="bah-20190331.xsd#BusinessSegmentInformation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/BusinessSegmentInformationDetails" xlink:href="bah-20190331.xsd#BusinessSegmentInformationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/CommitmentsAndContingencies" xlink:href="bah-20190331.xsd#CommitmentsAndContingencies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/CommitmentsAndContingenciesLeasesAndGuaranteesDetails" xlink:href="bah-20190331.xsd#CommitmentsAndContingenciesLeasesAndGuaranteesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/CommitmentsAndContingenciesLitigationDetails" xlink:href="bah-20190331.xsd#CommitmentsAndContingenciesLitigationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/CommitmentsAndContingenciesTables" xlink:href="bah-20190331.xsd#CommitmentsAndContingenciesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/ConsolidatedBalanceSheets" xlink:href="bah-20190331.xsd#ConsolidatedBalanceSheets" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/ConsolidatedBalanceSheetsParenthetical" xlink:href="bah-20190331.xsd#ConsolidatedBalanceSheetsParenthetical" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/ConsolidatedStatementsOfCashFlows" xlink:href="bah-20190331.xsd#ConsolidatedStatementsOfCashFlows" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/ConsolidatedStatementsOfComprehensiveIncome" xlink:href="bah-20190331.xsd#ConsolidatedStatementsOfComprehensiveIncome" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/ConsolidatedStatementsOfOperations" xlink:href="bah-20190331.xsd#ConsolidatedStatementsOfOperations" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/ConsolidatedStatementsOfStockholdersEquity" xlink:href="bah-20190331.xsd#ConsolidatedStatementsOfStockholdersEquity" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/Debt" xlink:href="bah-20190331.xsd#Debt" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/DebtNarrativeDetails" xlink:href="bah-20190331.xsd#DebtNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/DebtScheduleOfDebtDetails" xlink:href="bah-20190331.xsd#DebtScheduleOfDebtDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/DebtScheduleOfDetailOfInterestExpenseDetails" xlink:href="bah-20190331.xsd#DebtScheduleOfDetailOfInterestExpenseDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/DebtScheduleOfFutureDebtPrincipalRepaymentsDetails" xlink:href="bah-20190331.xsd#DebtScheduleOfFutureDebtPrincipalRepaymentsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/DebtTables" xlink:href="bah-20190331.xsd#DebtTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/DeferredPaymentObligation" xlink:href="bah-20190331.xsd#DeferredPaymentObligation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/DeferredPaymentObligationNarrativeDetails" xlink:href="bah-20190331.xsd#DeferredPaymentObligationNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/DeferredPaymentObligationReconciliationOfPrincipalBalanceOfDpoToRecordedAmountDetails" xlink:href="bah-20190331.xsd#DeferredPaymentObligationReconciliationOfPrincipalBalanceOfDpoToRecordedAmountDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/DeferredPaymentObligationTables" xlink:href="bah-20190331.xsd#DeferredPaymentObligationTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/Derivatives" xlink:href="bah-20190331.xsd#Derivatives" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/DerivativesNarrativeDetails" xlink:href="bah-20190331.xsd#DerivativesNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/DerivativesScheduleOfEffectOfDerivativesOnFinancialStatementsDetails" xlink:href="bah-20190331.xsd#DerivativesScheduleOfEffectOfDerivativesOnFinancialStatementsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/DerivativesTables" xlink:href="bah-20190331.xsd#DerivativesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/DocumentAndEntityInformation" xlink:href="bah-20190331.xsd#DocumentAndEntityInformation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/EarningsPerShare" xlink:href="bah-20190331.xsd#EarningsPerShare" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/EarningsPerShareDetails" xlink:href="bah-20190331.xsd#EarningsPerShareDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/EarningsPerShareTables" xlink:href="bah-20190331.xsd#EarningsPerShareTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/EmployeeBenefitPlans" xlink:href="bah-20190331.xsd#EmployeeBenefitPlans" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/EmployeeBenefitPlansAccumulatedOtherComprehensiveIncomeDetails" xlink:href="bah-20190331.xsd#EmployeeBenefitPlansAccumulatedOtherComprehensiveIncomeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/EmployeeBenefitPlansChangeInBenefitObligationAndChangeInPlanAssetsDetails" xlink:href="bah-20190331.xsd#EmployeeBenefitPlansChangeInBenefitObligationAndChangeInPlanAssetsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/EmployeeBenefitPlansComponentsOfNetPostretirementMedicalExpenseDetails" xlink:href="bah-20190331.xsd#EmployeeBenefitPlansComponentsOfNetPostretirementMedicalExpenseDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/EmployeeBenefitPlansFutureBenefitPaymentsDetails" xlink:href="bah-20190331.xsd#EmployeeBenefitPlansFutureBenefitPaymentsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/EmployeeBenefitPlansHealthcareCostTrendRatesDetails" xlink:href="bah-20190331.xsd#EmployeeBenefitPlansHealthcareCostTrendRatesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/EmployeeBenefitPlansNarrativeDetails" xlink:href="bah-20190331.xsd#EmployeeBenefitPlansNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/EmployeeBenefitPlansRetiredOfficersBonusPlanAndRetiredVpBonusPlanDetails" xlink:href="bah-20190331.xsd#EmployeeBenefitPlansRetiredOfficersBonusPlanAndRetiredVpBonusPlanDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/EmployeeBenefitPlansTables" xlink:href="bah-20190331.xsd#EmployeeBenefitPlansTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/EmployeeBenefitPlansWeightedAverageDiscountRateDetails" xlink:href="bah-20190331.xsd#EmployeeBenefitPlansWeightedAverageDiscountRateDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/FairValueMeasurements" xlink:href="bah-20190331.xsd#FairValueMeasurements" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/FairValueMeasurementsScheduleOfRecurringFairValueMeasurementsDetails" xlink:href="bah-20190331.xsd#FairValueMeasurementsScheduleOfRecurringFairValueMeasurementsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/FairValueMeasurementsTables" xlink:href="bah-20190331.xsd#FairValueMeasurementsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/GoodwillAndIntangibleAssets" xlink:href="bah-20190331.xsd#GoodwillAndIntangibleAssets" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/GoodwillAndIntangibleAssetsNarrativeDetails" xlink:href="bah-20190331.xsd#GoodwillAndIntangibleAssetsNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/GoodwillAndIntangibleAssetsScheduleOfExpectedAmortizationExpenseDetails" xlink:href="bah-20190331.xsd#GoodwillAndIntangibleAssetsScheduleOfExpectedAmortizationExpenseDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/GoodwillAndIntangibleAssetsScheduleOfFiniteLivedIntangibleAssetsDetails" xlink:href="bah-20190331.xsd#GoodwillAndIntangibleAssetsScheduleOfFiniteLivedIntangibleAssetsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/GoodwillAndIntangibleAssetsTables" xlink:href="bah-20190331.xsd#GoodwillAndIntangibleAssetsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/IncomeTaxes" xlink:href="bah-20190331.xsd#IncomeTaxes" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/IncomeTaxesComponentsOfIncomeTaxesDetails" xlink:href="bah-20190331.xsd#IncomeTaxesComponentsOfIncomeTaxesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/IncomeTaxesComponentsOfNetDeferredIncomeTaxesDetails" xlink:href="bah-20190331.xsd#IncomeTaxesComponentsOfNetDeferredIncomeTaxesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/IncomeTaxesNarrativeDetails" xlink:href="bah-20190331.xsd#IncomeTaxesNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/IncomeTaxesReconciliationOfIncomeTaxDetails" xlink:href="bah-20190331.xsd#IncomeTaxesReconciliationOfIncomeTaxDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/IncomeTaxesTables" xlink:href="bah-20190331.xsd#IncomeTaxesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/OtherLongTermLiabilities" xlink:href="bah-20190331.xsd#OtherLongTermLiabilities" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/OtherLongTermLiabilitiesDetails" xlink:href="bah-20190331.xsd#OtherLongTermLiabilitiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/OtherLongTermLiabilitiesTables" xlink:href="bah-20190331.xsd#OtherLongTermLiabilitiesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/PropertyAndEquipmentNet" xlink:href="bah-20190331.xsd#PropertyAndEquipmentNet" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/PropertyAndEquipmentNetDetails" xlink:href="bah-20190331.xsd#PropertyAndEquipmentNetDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/PropertyAndEquipmentNetTables" xlink:href="bah-20190331.xsd#PropertyAndEquipmentNetTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/RelatedPartyTransactions" xlink:href="bah-20190331.xsd#RelatedPartyTransactions" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/RelatedPartyTransactionsDetails" xlink:href="bah-20190331.xsd#RelatedPartyTransactionsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/Revenue" xlink:href="bah-20190331.xsd#Revenue" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/RevenueDisaggregationOfRevenueDetails" xlink:href="bah-20190331.xsd#RevenueDisaggregationOfRevenueDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/RevenueNarrativeDetails" xlink:href="bah-20190331.xsd#RevenueNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/RevenueSummaryOfContractBalancesDetails" xlink:href="bah-20190331.xsd#RevenueSummaryOfContractBalancesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/RevenueTables" xlink:href="bah-20190331.xsd#RevenueTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/StockBasedCompensation" xlink:href="bah-20190331.xsd#StockBasedCompensation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/StockBasedCompensationScheduleOfStockOptionsGrantedDetails" xlink:href="bah-20190331.xsd#StockBasedCompensationScheduleOfStockOptionsGrantedDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/StockBasedCompensationStockBasedCompensationExpenseDetails" xlink:href="bah-20190331.xsd#StockBasedCompensationStockBasedCompensationExpenseDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/StockBasedCompensationStockOptionAndRestrictedStockAwardActivityDetails" xlink:href="bah-20190331.xsd#StockBasedCompensationStockOptionAndRestrictedStockAwardActivityDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/StockBasedCompensationStockOptionAssumptionsDetails" xlink:href="bah-20190331.xsd#StockBasedCompensationStockOptionAssumptionsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/StockBasedCompensationSummaryOfStockPlansDetails" xlink:href="bah-20190331.xsd#StockBasedCompensationSummaryOfStockPlansDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/StockBasedCompensationSummaryOfUnrecognizedCompensationDetails" xlink:href="bah-20190331.xsd#StockBasedCompensationSummaryOfUnrecognizedCompensationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/StockBasedCompensationTables" xlink:href="bah-20190331.xsd#StockBasedCompensationTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/StockholdersEquity" xlink:href="bah-20190331.xsd#StockholdersEquity" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/StockholdersEquityNarrativeDetails" xlink:href="bah-20190331.xsd#StockholdersEquityNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/StockholdersEquitySummaryOfDividendsDetails" xlink:href="bah-20190331.xsd#StockholdersEquitySummaryOfDividendsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/StockholdersEquityTables" xlink:href="bah-20190331.xsd#StockholdersEquityTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/SubsequentEvents" xlink:href="bah-20190331.xsd#SubsequentEvents" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/SubsequentEventsDetails" xlink:href="bah-20190331.xsd#SubsequentEventsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/SummaryOfSignificantAccountingPolicies" xlink:href="bah-20190331.xsd#SummaryOfSignificantAccountingPolicies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/SummaryOfSignificantAccountingPoliciesIntangibleAssetsAndGoodwillDetails" xlink:href="bah-20190331.xsd#SummaryOfSignificantAccountingPoliciesIntangibleAssetsAndGoodwillDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:href="bah-20190331.xsd#SummaryOfSignificantAccountingPoliciesPolicies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/SummaryOfSignificantAccountingPoliciesPropertyPlantAndEquipmentDetails" xlink:href="bah-20190331.xsd#SummaryOfSignificantAccountingPoliciesPropertyPlantAndEquipmentDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/SummaryOfSignificantAccountingPoliciesRecentAccountingPronouncementsDetails" xlink:href="bah-20190331.xsd#SummaryOfSignificantAccountingPoliciesRecentAccountingPronouncementsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/SummaryOfSignificantAccountingPoliciesScheduleOfEffectOfAdoptionDetails" xlink:href="bah-20190331.xsd#SummaryOfSignificantAccountingPoliciesScheduleOfEffectOfAdoptionDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/SummaryOfSignificantAccountingPoliciesTables" xlink:href="bah-20190331.xsd#SummaryOfSignificantAccountingPoliciesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/SupplementalFinancialInformation" xlink:href="bah-20190331.xsd#SupplementalFinancialInformation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/SupplementalFinancialInformationDetails" xlink:href="bah-20190331.xsd#SupplementalFinancialInformationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/SupplementalFinancialInformationTables" xlink:href="bah-20190331.xsd#SupplementalFinancialInformationTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/UnauditedQuarterlyFinancialData" xlink:href="bah-20190331.xsd#UnauditedQuarterlyFinancialData" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/UnauditedQuarterlyFinancialDataDetails" xlink:href="bah-20190331.xsd#UnauditedQuarterlyFinancialDataDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/UnauditedQuarterlyFinancialDataTables" xlink:href="bah-20190331.xsd#UnauditedQuarterlyFinancialDataTables" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" xlink:type="simple" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccountsPayableAndOtherAccruedExpenses" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccountsPayableAndOtherAccruedExpensesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccountsPayableAndOtherAccruedExpensesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccountsReceivableNetOfAllowance" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccountsReceivableNetOfAllowanceDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccountsReceivableNetOfAllowanceTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccruedCompensationAndBenefits" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccruedCompensationAndBenefitsDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccruedCompensationAndBenefitsTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccumulatedOtherComprehensiveLoss" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccumulatedOtherComprehensiveLossScheduleOfChangesInAccumulatedOtherComprehensiveIncomeLossDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_8D58969CBA50138F6FC8EA7A4C8FDE41" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_22FB46A993FC551E9EDDEA7A4C8DC40D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_8D58969CBA50138F6FC8EA7A4C8FDE41" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_22FB46A993FC551E9EDDEA7A4C8DC40D" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_E9FD9CA8225EB057662EEA7A4C8D5C90" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_22FB46A993FC551E9EDDEA7A4C8DC40D" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_E9FD9CA8225EB057662EEA7A4C8D5C90" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_EB1B74FFE6FA44A5CB16EA7A4C8D6FD8_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_E9FD9CA8225EB057662EEA7A4C8D5C90" xlink:to="loc_us-gaap_EquityComponentDomain_EB1B74FFE6FA44A5CB16EA7A4C8D6FD8_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_EB1B74FFE6FA44A5CB16EA7A4C8D6FD8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_E9FD9CA8225EB057662EEA7A4C8D5C90" xlink:to="loc_us-gaap_EquityComponentDomain_EB1B74FFE6FA44A5CB16EA7A4C8D6FD8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_336066AA0F549AA4AF6DEA7A4C8EDB0B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_EB1B74FFE6FA44A5CB16EA7A4C8D6FD8" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_336066AA0F549AA4AF6DEA7A4C8EDB0B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember" xlink:label="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_2ECB38F76E7898537119EA8DE362EF33" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_EB1B74FFE6FA44A5CB16EA7A4C8D6FD8" xlink:to="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_2ECB38F76E7898537119EA8DE362EF33" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember" xlink:label="loc_us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember_87E88B23D3F90AEB1081EA8E76729552" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_EB1B74FFE6FA44A5CB16EA7A4C8D6FD8" xlink:to="loc_us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember_87E88B23D3F90AEB1081EA8E76729552" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_F75ED2BA50E81497B215EA7A4C8E9690" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_EB1B74FFE6FA44A5CB16EA7A4C8D6FD8" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_F75ED2BA50E81497B215EA7A4C8E9690" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AOCIAttributableToParentNetOfTaxRollForward" xlink:label="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_75E3E45F095EC182E819EA7A4C8FB1A8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_8D58969CBA50138F6FC8EA7A4C8FDE41" xlink:to="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_75E3E45F095EC182E819EA7A4C8FB1A8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity_1DBE8AAE21119ACB2E9CEA7A4C8FD3EF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_75E3E45F095EC182E819EA7A4C8FB1A8" xlink:to="loc_us-gaap_StockholdersEquity_1DBE8AAE21119ACB2E9CEA7A4C8FD3EF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent" xlink:label="loc_us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent_DA833B19D2C618C7A19EEA7A4C90A3A6" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_75E3E45F095EC182E819EA7A4C8FB1A8" xlink:to="loc_us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent_DA833B19D2C618C7A19EEA7A4C90A3A6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent" xlink:label="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_2126ECAE0CC5AEDBBAD4EA7A4C90E97C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_75E3E45F095EC182E819EA7A4C8FB1A8" xlink:to="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_2126ECAE0CC5AEDBBAD4EA7A4C90E97C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_7F8FEAF9BAE402AAD46CEA7A4C90B8F8" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_75E3E45F095EC182E819EA7A4C8FB1A8" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_7F8FEAF9BAE402AAD46CEA7A4C90B8F8" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_TaxCutsAndJobsActOf2017ReclassificationFromAOCIToRetainedEarnings" xlink:label="loc_bah_TaxCutsAndJobsActOf2017ReclassificationFromAOCIToRetainedEarnings_DABA4729D1D7894FF5FFEA7A4C90E32C" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_75E3E45F095EC182E819EA7A4C8FB1A8" xlink:to="loc_bah_TaxCutsAndJobsActOf2017ReclassificationFromAOCIToRetainedEarnings_DABA4729D1D7894FF5FFEA7A4C90E32C" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccumulatedOtherComprehensiveLossScheduleOfReclassificationsOutOfAccumulatedOtherComprehensiveLossToNetIncomeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems" xlink:label="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_923FAD29F6C46830DC1BD58B59CBD3A1" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_B3E8A3A56ED70C7FAE97D58B59C956CA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_923FAD29F6C46830DC1BD58B59CBD3A1" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_B3E8A3A56ED70C7FAE97D58B59C956CA" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis_3E976B0C2CE4328EA3E3D58B59C9CD69" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_B3E8A3A56ED70C7FAE97D58B59C956CA" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis_3E976B0C2CE4328EA3E3D58B59C9CD69" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_3F2872F5B49504C40437D58B59C9C69E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis_3E976B0C2CE4328EA3E3D58B59C9CD69" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_3F2872F5B49504C40437D58B59C9C69E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_3F2872F5B49504C40437D58B59C9C69E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis_3E976B0C2CE4328EA3E3D58B59C9CD69" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_3F2872F5B49504C40437D58B59C9C69E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember_1959BF363123EA5B0453D58B59C95D1D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_3F2872F5B49504C40437D58B59C9C69E" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember_1959BF363123EA5B0453D58B59C95D1D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_63A9C1A8F1D0990D8077D58B59CABF24" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_B3E8A3A56ED70C7FAE97D58B59C956CA" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_63A9C1A8F1D0990D8077D58B59CABF24" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_024315FF5C73B853EF58D58B59CAB73A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_63A9C1A8F1D0990D8077D58B59CABF24" xlink:to="loc_us-gaap_EquityComponentDomain_024315FF5C73B853EF58D58B59CAB73A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_024315FF5C73B853EF58D58B59CAB73A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_63A9C1A8F1D0990D8077D58B59CABF24" xlink:to="loc_us-gaap_EquityComponentDomain_024315FF5C73B853EF58D58B59CAB73A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_DEBA1D438DFBFFBD6DBFD58B59CA5B2B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_024315FF5C73B853EF58D58B59CAB73A" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_DEBA1D438DFBFFBD6DBFD58B59CA5B2B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_734C0AD44179B4889407D58B59CB5630" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_923FAD29F6C46830DC1BD58B59CBD3A1" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_734C0AD44179B4889407D58B59CB5630" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_6F360DE3765B824F1305D58B59CBEA32" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_923FAD29F6C46830DC1BD58B59CBD3A1" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_6F360DE3765B824F1305D58B59CBEA32" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_57BB209DAB722F4A72C1D58B59CBA4E0" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_923FAD29F6C46830DC1BD58B59CBD3A1" xlink:to="loc_us-gaap_NetIncomeLoss_57BB209DAB722F4A72C1D58B59CBA4E0" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccumulatedOtherComprehensiveLossTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/Acquisitions" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AcquisitionsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_4A6F0411203B4C044FBFD58B5B04A8AC" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8101929A2C0204557B4DD58B5B026607" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_4A6F0411203B4C044FBFD58B5B04A8AC" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8101929A2C0204557B4DD58B5B026607" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_EFA1EB297B81783D7813D58B5B0239CC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8101929A2C0204557B4DD58B5B026607" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_EFA1EB297B81783D7813D58B5B0239CC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_22610F477A789EBA6C01D58B5B02F1BD_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_EFA1EB297B81783D7813D58B5B0239CC" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_22610F477A789EBA6C01D58B5B02F1BD_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_22610F477A789EBA6C01D58B5B02F1BD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_EFA1EB297B81783D7813D58B5B0239CC" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_22610F477A789EBA6C01D58B5B02F1BD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="loc_us-gaap_CustomerRelationshipsMember_506BDE35C14F8E172993D58B5B02DB0F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_22610F477A789EBA6C01D58B5B02F1BD" xlink:to="loc_us-gaap_CustomerRelationshipsMember_506BDE35C14F8E172993D58B5B02DB0F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_97E2BFA640306310659FD58B5B03D012" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8101929A2C0204557B4DD58B5B026607" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_97E2BFA640306310659FD58B5B03D012" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8BDA10ED2780327E73D4D58B5B036EF9_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_97E2BFA640306310659FD58B5B03D012" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8BDA10ED2780327E73D4D58B5B036EF9_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8BDA10ED2780327E73D4D58B5B036EF9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_97E2BFA640306310659FD58B5B03D012" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8BDA10ED2780327E73D4D58B5B036EF9" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_EGovHoldingsInc.dbaAquilentMember" xlink:label="loc_bah_EGovHoldingsInc.dbaAquilentMember_A55DAC6496F158CE5FC5D58B5B03E9EB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8BDA10ED2780327E73D4D58B5B036EF9" xlink:to="loc_bah_EGovHoldingsInc.dbaAquilentMember_A55DAC6496F158CE5FC5D58B5B03E9EB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferred1" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_7BC9208373109C946353D58B5B04BEA2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_4A6F0411203B4C044FBFD58B5B04A8AC" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_7BC9208373109C946353D58B5B04BEA2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_43C52886198C7C81E2BBD58B5B045783" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_4A6F0411203B4C044FBFD58B5B04A8AC" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_43C52886198C7C81E2BBD58B5B045783" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_82024A2E9BA78932BE2AD58B5B0489D2" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_4A6F0411203B4C044FBFD58B5B04A8AC" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_82024A2E9BA78932BE2AD58B5B0489D2" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_BusinessCombinationTaxIndemnificationLiability" xlink:label="loc_bah_BusinessCombinationTaxIndemnificationLiability_7EC4F374A33CD6005095D58B5B05B7F3" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_4A6F0411203B4C044FBFD58B5B04A8AC" xlink:to="loc_bah_BusinessCombinationTaxIndemnificationLiability_7EC4F374A33CD6005095D58B5B05B7F3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LiabilityForUncertainTaxPositionsNoncurrent" xlink:label="loc_us-gaap_LiabilityForUncertainTaxPositionsNoncurrent_217E508B037386063B4CD58B5B058A39" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_4A6F0411203B4C044FBFD58B5B04A8AC" xlink:to="loc_us-gaap_LiabilityForUncertainTaxPositionsNoncurrent_217E508B037386063B4CD58B5B058A39" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_9269F9333DC879036F64D58B5B05D8E5" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_4A6F0411203B4C044FBFD58B5B04A8AC" xlink:to="loc_us-gaap_Goodwill_9269F9333DC879036F64D58B5B05D8E5" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AcquisitionsScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_6B9B97034E6FA02C6E97EA0F8EF7B46A" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2063C1976BCD38D4E963EA0F8EF6ADBC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_6B9B97034E6FA02C6E97EA0F8EF7B46A" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2063C1976BCD38D4E963EA0F8EF6ADBC" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_1DADAC7372C0777CEFB0EA0F8EF6895A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2063C1976BCD38D4E963EA0F8EF6ADBC" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_1DADAC7372C0777CEFB0EA0F8EF6895A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_62ACAC0B4F58F0F36F4DEA0F8EF74C12_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_1DADAC7372C0777CEFB0EA0F8EF6895A" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_62ACAC0B4F58F0F36F4DEA0F8EF74C12_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_62ACAC0B4F58F0F36F4DEA0F8EF74C12" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_1DADAC7372C0777CEFB0EA0F8EF6895A" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_62ACAC0B4F58F0F36F4DEA0F8EF74C12" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_EGovHoldingsInc.dbaAquilentMember" xlink:label="loc_bah_EGovHoldingsInc.dbaAquilentMember_B80122FAB7311811CD23EA0F8EF788AA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_62ACAC0B4F58F0F36F4DEA0F8EF74C12" xlink:to="loc_bah_EGovHoldingsInc.dbaAquilentMember_B80122FAB7311811CD23EA0F8EF788AA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets_EFE105ECD7AAE6788F6DEA0F8EF8BBE1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_6B9B97034E6FA02C6E97EA0F8EF7B46A" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets_EFE105ECD7AAE6788F6DEA0F8EF8BBE1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_3FEF45E056A057D0B93EEA0F8EF8A02A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_6B9B97034E6FA02C6E97EA0F8EF7B46A" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_3FEF45E056A057D0B93EEA0F8EF8A02A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_BB89434FA8A849AF483FEA0F8EF8E288" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_6B9B97034E6FA02C6E97EA0F8EF7B46A" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_BB89434FA8A849AF483FEA0F8EF8E288" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_4D55CCD37ED7CFA3CEC8EA0F8EF8361C" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_6B9B97034E6FA02C6E97EA0F8EF7B46A" xlink:to="loc_us-gaap_Goodwill_4D55CCD37ED7CFA3CEC8EA0F8EF8361C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilities" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilities_E2894A8FE9812A5C63D8EA0F8EF9B222" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_6B9B97034E6FA02C6E97EA0F8EF7B46A" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilities_E2894A8FE9812A5C63D8EA0F8EF9B222" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_BusinessCombinationTaxIndemnificationLiability" xlink:label="loc_bah_BusinessCombinationTaxIndemnificationLiability_24EF740A2A349536C505EA0F8EF93CA9" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_6B9B97034E6FA02C6E97EA0F8EF7B46A" xlink:to="loc_bah_BusinessCombinationTaxIndemnificationLiability_24EF740A2A349536C505EA0F8EF93CA9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LiabilityForUncertainTaxPositionsNoncurrent" xlink:label="loc_us-gaap_LiabilityForUncertainTaxPositionsNoncurrent_B68F9A83D852623D026EEA0F8EF9188D" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_6B9B97034E6FA02C6E97EA0F8EF7B46A" xlink:to="loc_us-gaap_LiabilityForUncertainTaxPositionsNoncurrent_B68F9A83D852623D026EEA0F8EF9188D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_472AEBF8387CA7B49513EA0F8EF9CB46" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_6B9B97034E6FA02C6E97EA0F8EF7B46A" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_472AEBF8387CA7B49513EA0F8EF9CB46" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AcquisitionsTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/BusinessOverview" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/BusinessOverviewDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/BusinessSegmentInformation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/BusinessSegmentInformationDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/CommitmentsAndContingencies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/CommitmentsAndContingenciesLeasesAndGuaranteesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskLineItems" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_75C10F9C66B6A42427C7D58B581D825F" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskTable" xlink:label="loc_us-gaap_ConcentrationRiskTable_7E22E0D57F31BCB3E80ED58B581C1FFF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_75C10F9C66B6A42427C7D58B581D825F" xlink:to="loc_us-gaap_ConcentrationRiskTable_7E22E0D57F31BCB3E80ED58B581C1FFF" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GuaranteeObligationsByNatureAxis" xlink:label="loc_us-gaap_GuaranteeObligationsByNatureAxis_3687B21FA99C96B5D92AD58B581C5CE4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_7E22E0D57F31BCB3E80ED58B581C1FFF" xlink:to="loc_us-gaap_GuaranteeObligationsByNatureAxis_3687B21FA99C96B5D92AD58B581C5CE4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GuaranteeObligationsNatureDomain" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain_00D2F024AC24CDB6A3B4D58B581C74A9_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis_3687B21FA99C96B5D92AD58B581C5CE4" xlink:to="loc_us-gaap_GuaranteeObligationsNatureDomain_00D2F024AC24CDB6A3B4D58B581C74A9_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GuaranteeObligationsNatureDomain" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain_00D2F024AC24CDB6A3B4D58B581C74A9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis_3687B21FA99C96B5D92AD58B581C5CE4" xlink:to="loc_us-gaap_GuaranteeObligationsNatureDomain_00D2F024AC24CDB6A3B4D58B581C74A9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinancialStandbyLetterOfCreditMember" xlink:label="loc_us-gaap_FinancialStandbyLetterOfCreditMember_B83287EC45D7DC587734D58B581C7250" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsNatureDomain_00D2F024AC24CDB6A3B4D58B581C74A9" xlink:to="loc_us-gaap_FinancialStandbyLetterOfCreditMember_B83287EC45D7DC587734D58B581C7250" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_7299B8B22ABBB4C848B9D58B581D402F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_7E22E0D57F31BCB3E80ED58B581C1FFF" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_7299B8B22ABBB4C848B9D58B581D402F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_8C0F26F73D30A6E42059D58B581D8C38_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_7299B8B22ABBB4C848B9D58B581D402F" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_8C0F26F73D30A6E42059D58B581D8C38_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_8C0F26F73D30A6E42059D58B581D8C38" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_7299B8B22ABBB4C848B9D58B581D402F" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_8C0F26F73D30A6E42059D58B581D8C38" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GovernmentContractsConcentrationRiskMember" xlink:label="loc_us-gaap_GovernmentContractsConcentrationRiskMember_C7FC038CB1506BC271EFD58B581D93CD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_8C0F26F73D30A6E42059D58B581D8C38" xlink:to="loc_us-gaap_GovernmentContractsConcentrationRiskMember_C7FC038CB1506BC271EFD58B581D93CD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GuaranteeObligationsCurrentCarryingValue" xlink:label="loc_us-gaap_GuaranteeObligationsCurrentCarryingValue_57A46438D20010AEE6B3D58B581DBA65" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_75C10F9C66B6A42427C7D58B581D825F" xlink:to="loc_us-gaap_GuaranteeObligationsCurrentCarryingValue_57A46438D20010AEE6B3D58B581DBA65" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GuaranteeObligationsLiquidationProceeds" xlink:label="loc_us-gaap_GuaranteeObligationsLiquidationProceeds_261874320939E03007CFD58B581ED1A2" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_75C10F9C66B6A42427C7D58B581D825F" xlink:to="loc_us-gaap_GuaranteeObligationsLiquidationProceeds_261874320939E03007CFD58B581ED1A2" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_GuarantorObligationsFacility" xlink:label="loc_bah_GuarantorObligationsFacility_D43C385BD056C55EEB20D58B581E97B5" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_75C10F9C66B6A42427C7D58B581D825F" xlink:to="loc_bah_GuarantorObligationsFacility_D43C385BD056C55EEB20D58B581E97B5" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_GuarantorObligationsAvailableAmount" xlink:label="loc_bah_GuarantorObligationsAvailableAmount_7BF435771AB2A021FAB7D58B581F5DB8" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_75C10F9C66B6A42427C7D58B581D825F" xlink:to="loc_bah_GuarantorObligationsAvailableAmount_7BF435771AB2A021FAB7D58B581F5DB8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_E3060B00EEF7DE89F425D58B581F4A2D" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_75C10F9C66B6A42427C7D58B581D825F" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_E3060B00EEF7DE89F425D58B581F4A2D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingenciesLineItems" xlink:label="loc_us-gaap_LossContingenciesLineItems_1E8EFDA21AEFCAEF0098D58B5820E675" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingenciesTable" xlink:label="loc_us-gaap_LossContingenciesTable_90CA7133E8A8508E1570D58B581FE926" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_1E8EFDA21AEFCAEF0098D58B5820E675" xlink:to="loc_us-gaap_LossContingenciesTable_90CA7133E8A8508E1570D58B581FE926" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_95FB766BF223BB6C98D7D58B581FFAC1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_90CA7133E8A8508E1570D58B581FE926" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_95FB766BF223BB6C98D7D58B581FFAC1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_360FF55791B62E6B859BD58B582035AC_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_95FB766BF223BB6C98D7D58B581FFAC1" xlink:to="loc_us-gaap_LossContingencyNatureDomain_360FF55791B62E6B859BD58B582035AC_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_360FF55791B62E6B859BD58B582035AC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_95FB766BF223BB6C98D7D58B581FFAC1" xlink:to="loc_us-gaap_LossContingencyNatureDomain_360FF55791B62E6B859BD58B582035AC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_UnfavorableRegulatoryActionMember" xlink:label="loc_us-gaap_UnfavorableRegulatoryActionMember_91CE3EC0031899C7237BD58B5820DAB7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_360FF55791B62E6B859BD58B582035AC" xlink:to="loc_us-gaap_UnfavorableRegulatoryActionMember_91CE3EC0031899C7237BD58B5820DAB7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyAccrualAtCarryingValue" xlink:label="loc_us-gaap_LossContingencyAccrualAtCarryingValue_DD730AD02580B51FC7F9D58B5825A4CE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_1E8EFDA21AEFCAEF0098D58B5820E675" xlink:to="loc_us-gaap_LossContingencyAccrualAtCarryingValue_DD730AD02580B51FC7F9D58B5825A4CE" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/CommitmentsAndContingenciesLitigationDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingenciesLineItems" xlink:label="loc_us-gaap_LossContingenciesLineItems_6D787BD1B9AC792A060FD6ECB2AE31BF" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingenciesTable" xlink:label="loc_us-gaap_LossContingenciesTable_9A116807EA51FF184288D6ECB2AB4803" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_6D787BD1B9AC792A060FD6ECB2AE31BF" xlink:to="loc_us-gaap_LossContingenciesTable_9A116807EA51FF184288D6ECB2AB4803" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_LitigationCaseAxis" xlink:label="loc_srt_LitigationCaseAxis_8086636707DC58B0137ED6ECD81C6915" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_9A116807EA51FF184288D6ECB2AB4803" xlink:to="loc_srt_LitigationCaseAxis_8086636707DC58B0137ED6ECD81C6915" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_LitigationCaseTypeDomain" xlink:label="loc_srt_LitigationCaseTypeDomain_F727B0EB6C3D5A3F1D0BD6ECD99C125E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_8086636707DC58B0137ED6ECD81C6915" xlink:to="loc_srt_LitigationCaseTypeDomain_F727B0EB6C3D5A3F1D0BD6ECD99C125E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_LitigationCaseTypeDomain" xlink:label="loc_srt_LitigationCaseTypeDomain_F727B0EB6C3D5A3F1D0BD6ECD99C125E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_8086636707DC58B0137ED6ECD81C6915" xlink:to="loc_srt_LitigationCaseTypeDomain_F727B0EB6C3D5A3F1D0BD6ECD99C125E" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_UnitedStatesDistrictCourtForTheEasternDistrictOfVirginiaStyledLangleyV.BoozAllenHamiltonHoldingCorp.Member" xlink:label="loc_bah_UnitedStatesDistrictCourtForTheEasternDistrictOfVirginiaStyledLangleyV.BoozAllenHamiltonHoldingCorp.Member_42D2DE046E1027AD7746D6ECD8C942B3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_F727B0EB6C3D5A3F1D0BD6ECD99C125E" xlink:to="loc_bah_UnitedStatesDistrictCourtForTheEasternDistrictOfVirginiaStyledLangleyV.BoozAllenHamiltonHoldingCorp.Member_42D2DE046E1027AD7746D6ECD8C942B3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_DCDACB9D360D670988F1D6ECB2ACFE41" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_9A116807EA51FF184288D6ECB2AB4803" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_DCDACB9D360D670988F1D6ECB2ACFE41" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_2FCFEA7C259E5538A10AD6ECB2AC7B38_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_DCDACB9D360D670988F1D6ECB2ACFE41" xlink:to="loc_us-gaap_LossContingencyNatureDomain_2FCFEA7C259E5538A10AD6ECB2AC7B38_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_2FCFEA7C259E5538A10AD6ECB2AC7B38" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_DCDACB9D360D670988F1D6ECB2ACFE41" xlink:to="loc_us-gaap_LossContingencyNatureDomain_2FCFEA7C259E5538A10AD6ECB2AC7B38" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_FormerStockholderLitigationMember" xlink:label="loc_bah_FormerStockholderLitigationMember_F2B84CE1880F2870419ED6ECB2ACD231" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_2FCFEA7C259E5538A10AD6ECB2AC7B38" xlink:to="loc_bah_FormerStockholderLitigationMember_F2B84CE1880F2870419ED6ECB2ACD231" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_LitigationCourtAxis" xlink:label="loc_bah_LitigationCourtAxis_86D160B5C834A89E126CD6ECB2ADE793" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_9A116807EA51FF184288D6ECB2AB4803" xlink:to="loc_bah_LitigationCourtAxis_86D160B5C834A89E126CD6ECB2ADE793" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_LitigationCourtTypeDomain" xlink:label="loc_bah_LitigationCourtTypeDomain_1270C14240143C8B67E7D6ECB2AD499A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_bah_LitigationCourtAxis_86D160B5C834A89E126CD6ECB2ADE793" xlink:to="loc_bah_LitigationCourtTypeDomain_1270C14240143C8B67E7D6ECB2AD499A_default" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_LitigationCourtTypeDomain" xlink:label="loc_bah_LitigationCourtTypeDomain_1270C14240143C8B67E7D6ECB2AD499A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_bah_LitigationCourtAxis_86D160B5C834A89E126CD6ECB2ADE793" xlink:to="loc_bah_LitigationCourtTypeDomain_1270C14240143C8B67E7D6ECB2AD499A" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_UnitedStatesCourtofAppealsfortheNinthCircuitMember" xlink:label="loc_bah_UnitedStatesCourtofAppealsfortheNinthCircuitMember_96C3386D05F235531D10D6ECB2ADE2FC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_LitigationCourtTypeDomain_1270C14240143C8B67E7D6ECB2AD499A" xlink:to="loc_bah_UnitedStatesCourtofAppealsfortheNinthCircuitMember_96C3386D05F235531D10D6ECB2ADE2FC" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_UnitedStatesCourtofAppealsfortheSecondCircuitMember" xlink:label="loc_bah_UnitedStatesCourtofAppealsfortheSecondCircuitMember_8658F3755D1D9C225B6FD6ECB2AE2C2D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_LitigationCourtTypeDomain_1270C14240143C8B67E7D6ECB2AD499A" xlink:to="loc_bah_UnitedStatesCourtofAppealsfortheSecondCircuitMember_8658F3755D1D9C225B6FD6ECB2AE2C2D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyNumberOfPlaintiffs" xlink:label="loc_us-gaap_LossContingencyNumberOfPlaintiffs_230BE47CB37A74D2A00BD6ECB2AE9C74" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_6D787BD1B9AC792A060FD6ECB2AE31BF" xlink:to="loc_us-gaap_LossContingencyNumberOfPlaintiffs_230BE47CB37A74D2A00BD6ECB2AE9C74" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyNewClaimsFiledNumber" xlink:label="loc_us-gaap_LossContingencyNewClaimsFiledNumber_EB8916B112B0B2195EAAD6ECB2AF2BD1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_6D787BD1B9AC792A060FD6ECB2AE31BF" xlink:to="loc_us-gaap_LossContingencyNewClaimsFiledNumber_EB8916B112B0B2195EAAD6ECB2AF2BD1" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_LossContingencyClaimsAmendedNumber" xlink:label="loc_bah_LossContingencyClaimsAmendedNumber_C4F83475346A40F48C83D6ECB2AF8312" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_6D787BD1B9AC792A060FD6ECB2AE31BF" xlink:to="loc_bah_LossContingencyClaimsAmendedNumber_C4F83475346A40F48C83D6ECB2AF8312" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyPendingClaimsNumber" xlink:label="loc_us-gaap_LossContingencyPendingClaimsNumber_C508409BC03F2AC2E28BD6ECB2AF5831" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_6D787BD1B9AC792A060FD6ECB2AE31BF" xlink:to="loc_us-gaap_LossContingencyPendingClaimsNumber_C508409BC03F2AC2E28BD6ECB2AF5831" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyClaimsSettledAndDismissedNumber" xlink:label="loc_us-gaap_LossContingencyClaimsSettledAndDismissedNumber_8A9CE5105527425B1030D6ECB2B0AAF9" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_6D787BD1B9AC792A060FD6ECB2AE31BF" xlink:to="loc_us-gaap_LossContingencyClaimsSettledAndDismissedNumber_8A9CE5105527425B1030D6ECB2B0AAF9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyClaimsSettledNumber" xlink:label="loc_us-gaap_LossContingencyClaimsSettledNumber_197AA8A17344E6DF292BD6ECB2B03CA6" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_6D787BD1B9AC792A060FD6ECB2AE31BF" xlink:to="loc_us-gaap_LossContingencyClaimsSettledNumber_197AA8A17344E6DF292BD6ECB2B03CA6" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/CommitmentsAndContingenciesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/ConsolidatedBalanceSheets" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/ConsolidatedBalanceSheetsParenthetical" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/ConsolidatedStatementsOfCashFlows" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/ConsolidatedStatementsOfComprehensiveIncome" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/ConsolidatedStatementsOfOperations" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/ConsolidatedStatementsOfStockholdersEquity" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_321D4EBDEE82C7EFE23CEA7A4FAA6C84" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_70FE46D3919969682D7CEA7A4FA79DD2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_321D4EBDEE82C7EFE23CEA7A4FAA6C84" xlink:to="loc_us-gaap_StatementTable_70FE46D3919969682D7CEA7A4FA79DD2" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_B545BF03EDA875221E36EA7A4FA7403D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_70FE46D3919969682D7CEA7A4FA79DD2" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_B545BF03EDA875221E36EA7A4FA7403D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_E60FEB3ACD4A56933239EA7A4FA70F10_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_B545BF03EDA875221E36EA7A4FA7403D" xlink:to="loc_us-gaap_EquityComponentDomain_E60FEB3ACD4A56933239EA7A4FA70F10_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_E60FEB3ACD4A56933239EA7A4FA70F10" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_B545BF03EDA875221E36EA7A4FA7403D" xlink:to="loc_us-gaap_EquityComponentDomain_E60FEB3ACD4A56933239EA7A4FA70F10" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_A49C1ECC82285D7B29C8EA7A4FA89140" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_E60FEB3ACD4A56933239EA7A4FA70F10" xlink:to="loc_us-gaap_CommonStockMember_A49C1ECC82285D7B29C8EA7A4FA89140" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockMember" xlink:label="loc_us-gaap_TreasuryStockMember_4B0419E11E24BE8E65B1EA7A4FA8A6F0" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_E60FEB3ACD4A56933239EA7A4FA70F10" xlink:to="loc_us-gaap_TreasuryStockMember_4B0419E11E24BE8E65B1EA7A4FA8A6F0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_158C948E97D28A738BEDEA7A4FA8DE99" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_E60FEB3ACD4A56933239EA7A4FA70F10" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_158C948E97D28A738BEDEA7A4FA8DE99" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaap_RetainedEarningsMember_4F56B827EC845F70E49BEA7A4FA808ED" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_E60FEB3ACD4A56933239EA7A4FA70F10" xlink:to="loc_us-gaap_RetainedEarningsMember_4F56B827EC845F70E49BEA7A4FA808ED" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_6A6897C4E1682CB227A3EA7A4FA91DC6" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_E60FEB3ACD4A56933239EA7A4FA70F10" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_6A6897C4E1682CB227A3EA7A4FA91DC6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_B09E4894FFD73C22BB7DEA7A4FA9EED9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_70FE46D3919969682D7CEA7A4FA79DD2" xlink:to="loc_us-gaap_StatementClassOfStockAxis_B09E4894FFD73C22BB7DEA7A4FA9EED9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_C93B804A8EB283A716E8EA7A4FA960C9_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_B09E4894FFD73C22BB7DEA7A4FA9EED9" xlink:to="loc_us-gaap_ClassOfStockDomain_C93B804A8EB283A716E8EA7A4FA960C9_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_C93B804A8EB283A716E8EA7A4FA960C9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_B09E4894FFD73C22BB7DEA7A4FA9EED9" xlink:to="loc_us-gaap_ClassOfStockDomain_C93B804A8EB283A716E8EA7A4FA960C9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonClassAMember" xlink:label="loc_us-gaap_CommonClassAMember_DCD218D444A576C17FB6EA7A4FA9FB7C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_C93B804A8EB283A716E8EA7A4FA960C9" xlink:to="loc_us-gaap_CommonClassAMember_DCD218D444A576C17FB6EA7A4FA9FB7C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_11A4C958D5D4E6160DECEA7A4FAA6F0D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_321D4EBDEE82C7EFE23CEA7A4FAA6C84" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_11A4C958D5D4E6160DECEA7A4FAA6F0D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharesOutstanding" xlink:label="loc_us-gaap_SharesOutstanding_8E05E410EA9259CE46EBEA7A4FAA353D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_11A4C958D5D4E6160DECEA7A4FAA6F0D" xlink:to="loc_us-gaap_SharesOutstanding_8E05E410EA9259CE46EBEA7A4FAA353D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity_4BA6EEDF60F857F468BCEA7A4FAB310E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_11A4C958D5D4E6160DECEA7A4FAA6F0D" xlink:to="loc_us-gaap_StockholdersEquity_4BA6EEDF60F857F468BCEA7A4FAB310E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_17B2183076C330FF39F7EA7A4FAB9667" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_11A4C958D5D4E6160DECEA7A4FAA6F0D" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_17B2183076C330FF39F7EA7A4FAB9667" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_99FFC3A0DDA6A3314CE1EA7A4FAB3F2C" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_11A4C958D5D4E6160DECEA7A4FAA6F0D" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_99FFC3A0DDA6A3314CE1EA7A4FAB3F2C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_D41EA324F7FFD4B67B7EEA7A4FAB965D" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_11A4C958D5D4E6160DECEA7A4FAA6F0D" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_D41EA324F7FFD4B67B7EEA7A4FAB965D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_3F4C0ED74645CA808920EA7A4FAB0333" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_11A4C958D5D4E6160DECEA7A4FAA6F0D" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_3F4C0ED74645CA808920EA7A4FAB0333" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation_7EC68197570A0D46E089EA7A4FABAB86" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_11A4C958D5D4E6160DECEA7A4FAA6F0D" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation_7EC68197570A0D46E089EA7A4FABAB86" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockSharesAcquired" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_BE8C211FDE91D1F421E3EA7A4FAC0E0F" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_11A4C958D5D4E6160DECEA7A4FAA6F0D" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_BE8C211FDE91D1F421E3EA7A4FAC0E0F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_EDCE5DC2C0CCED177810EA7A4FAC777E" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_11A4C958D5D4E6160DECEA7A4FAA6F0D" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_EDCE5DC2C0CCED177810EA7A4FAC777E" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_AdjustmentsToAdditionalPaidInCapitalRecognitionOfLiabilityRelatedToFutureStockOptionExercises" xlink:label="loc_bah_AdjustmentsToAdditionalPaidInCapitalRecognitionOfLiabilityRelatedToFutureStockOptionExercises_9142515A92DFA047FD74EA7A4FAC1F82" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_11A4C958D5D4E6160DECEA7A4FAA6F0D" xlink:to="loc_bah_AdjustmentsToAdditionalPaidInCapitalRecognitionOfLiabilityRelatedToFutureStockOptionExercises_9142515A92DFA047FD74EA7A4FAC1F82" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_BFBE1FC631E0E9318D00EA7A4FACC14C" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_11A4C958D5D4E6160DECEA7A4FAA6F0D" xlink:to="loc_us-gaap_NetIncomeLoss_BFBE1FC631E0E9318D00EA7A4FACC14C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption" xlink:label="loc_us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption_47B57CBC025689AC2CE1EA7A4FAC966A" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_11A4C958D5D4E6160DECEA7A4FAA6F0D" xlink:to="loc_us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption_47B57CBC025689AC2CE1EA7A4FAC966A" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_TaxCutsAndJobsActOf2017ReclassificationFromAOCIToRetainedEarnings" xlink:label="loc_bah_TaxCutsAndJobsActOf2017ReclassificationFromAOCIToRetainedEarnings_9BF8B20F63DA5F92F737EA7A4FAD05D3" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_11A4C958D5D4E6160DECEA7A4FAA6F0D" xlink:to="loc_bah_TaxCutsAndJobsActOf2017ReclassificationFromAOCIToRetainedEarnings_9BF8B20F63DA5F92F737EA7A4FAD05D3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_54B78A60D6D03AB9FE3EEA7A4FAD02CE" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_11A4C958D5D4E6160DECEA7A4FAA6F0D" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_54B78A60D6D03AB9FE3EEA7A4FAD02CE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DividendsCash" xlink:label="loc_us-gaap_DividendsCash_940DF772672E5D9C65A0EA7A4FAD6702" xlink:type="locator" />
    <link:definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_11A4C958D5D4E6160DECEA7A4FAA6F0D" xlink:to="loc_us-gaap_DividendsCash_940DF772672E5D9C65A0EA7A4FAD6702" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_76125CDB431F668C8E84EA7A4FAD7D58" xlink:type="locator" />
    <link:definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_11A4C958D5D4E6160DECEA7A4FAA6F0D" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_76125CDB431F668C8E84EA7A4FAD7D58" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/Debt" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DebtNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_7D26ACE68AAF67FB3610EB25193DB185" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_532F6840328A337A2896EB2519355D0D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7D26ACE68AAF67FB3610EB25193DB185" xlink:to="loc_us-gaap_DebtInstrumentTable_532F6840328A337A2896EB2519355D0D" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_FF8CC095F385E4DD2FBCEB2519353A86" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_532F6840328A337A2896EB2519355D0D" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_FF8CC095F385E4DD2FBCEB2519353A86" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_88920E5440F5886A3332EB2519367AD0_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_FF8CC095F385E4DD2FBCEB2519353A86" xlink:to="loc_us-gaap_HedgingRelationshipDomain_88920E5440F5886A3332EB2519367AD0_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_88920E5440F5886A3332EB2519367AD0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_FF8CC095F385E4DD2FBCEB2519353A86" xlink:to="loc_us-gaap_HedgingRelationshipDomain_88920E5440F5886A3332EB2519367AD0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CashFlowHedgingMember" xlink:label="loc_us-gaap_CashFlowHedgingMember_27A3BB83A193B8BA348AEB2519363A32" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_88920E5440F5886A3332EB2519367AD0" xlink:to="loc_us-gaap_CashFlowHedgingMember_27A3BB83A193B8BA348AEB2519363A32" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_64A8F9D5DB68679015F0EB251937C698" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_532F6840328A337A2896EB2519355D0D" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_64A8F9D5DB68679015F0EB251937C698" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_883E5C8185507B9C2F9DEB2519376C2F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_64A8F9D5DB68679015F0EB251937C698" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_883E5C8185507B9C2F9DEB2519376C2F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_883E5C8185507B9C2F9DEB2519376C2F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_64A8F9D5DB68679015F0EB251937C698" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_883E5C8185507B9C2F9DEB2519376C2F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_2ADD146BFC9160B5E21AEB251937C4B8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_883E5C8185507B9C2F9DEB2519376C2F" xlink:to="loc_us-gaap_InterestRateSwapMember_2ADD146BFC9160B5E21AEB251937C4B8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationAxis" xlink:label="loc_us-gaap_HedgingDesignationAxis_634F84C7380D7822F4CAEB25193755B6" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_532F6840328A337A2896EB2519355D0D" xlink:to="loc_us-gaap_HedgingDesignationAxis_634F84C7380D7822F4CAEB25193755B6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_43B07F5938B27043CE6BEB2519386A80_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_634F84C7380D7822F4CAEB25193755B6" xlink:to="loc_us-gaap_HedgingDesignationDomain_43B07F5938B27043CE6BEB2519386A80_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_43B07F5938B27043CE6BEB2519386A80" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_634F84C7380D7822F4CAEB25193755B6" xlink:to="loc_us-gaap_HedgingDesignationDomain_43B07F5938B27043CE6BEB2519386A80" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DesignatedAsHedgingInstrumentMember" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_FED37805AE104DAF4B6FEB2519386E17" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_43B07F5938B27043CE6BEB2519386A80" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_FED37805AE104DAF4B6FEB2519386E17" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_AF5642DE3A06FE7F7F10EB2519380372" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_532F6840328A337A2896EB2519355D0D" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_AF5642DE3A06FE7F7F10EB2519380372" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_A7F788D2052D0983586DEB251938692B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_AF5642DE3A06FE7F7F10EB2519380372" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_A7F788D2052D0983586DEB251938692B_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_A7F788D2052D0983586DEB251938692B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_AF5642DE3A06FE7F7F10EB2519380372" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_A7F788D2052D0983586DEB251938692B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SecuredDebtMember" xlink:label="loc_us-gaap_SecuredDebtMember_688B4475A9188640DD57EB2519399111" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_A7F788D2052D0983586DEB251938692B" xlink:to="loc_us-gaap_SecuredDebtMember_688B4475A9188640DD57EB2519399111" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_0BAE964D971652CAE3DDEB2519391697" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_A7F788D2052D0983586DEB251938692B" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_0BAE964D971652CAE3DDEB2519391697" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LetterOfCreditMember" xlink:label="loc_us-gaap_LetterOfCreditMember_BF427A2116E36581FFC7EB2519396D9C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_A7F788D2052D0983586DEB251938692B" xlink:to="loc_us-gaap_LetterOfCreditMember_BF427A2116E36581FFC7EB2519396D9C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SeniorNotesMember" xlink:label="loc_us-gaap_SeniorNotesMember_43D1E4C6070610822386EB2519399244" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_A7F788D2052D0983586DEB251938692B" xlink:to="loc_us-gaap_SeniorNotesMember_43D1E4C6070610822386EB2519399244" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_061C1549AA55AFC78C36EB251939FB37" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_532F6840328A337A2896EB2519355D0D" xlink:to="loc_us-gaap_DebtInstrumentAxis_061C1549AA55AFC78C36EB251939FB37" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_60EBD3A59C2CE49AC6F8EB25193A0719_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_061C1549AA55AFC78C36EB251939FB37" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_60EBD3A59C2CE49AC6F8EB25193A0719_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_60EBD3A59C2CE49AC6F8EB25193A0719" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_061C1549AA55AFC78C36EB251939FB37" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_60EBD3A59C2CE49AC6F8EB25193A0719" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DelayedDrawFacilityMember" xlink:label="loc_bah_DelayedDrawFacilityMember_D0EB625F901A709D9C4FEB25193A45BD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_60EBD3A59C2CE49AC6F8EB25193A0719" xlink:to="loc_bah_DelayedDrawFacilityMember_D0EB625F901A709D9C4FEB25193A45BD" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_TrancheBLoansMember" xlink:label="loc_bah_TrancheBLoansMember_6D6014026E587A293806EB25193A4BCF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_60EBD3A59C2CE49AC6F8EB25193A0719" xlink:to="loc_bah_TrancheBLoansMember_6D6014026E587A293806EB25193A4BCF" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_TrancheALoansMember" xlink:label="loc_bah_TrancheALoansMember_887C8CB8782E9F808DF8EB25193A0272" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_60EBD3A59C2CE49AC6F8EB25193A0719" xlink:to="loc_bah_TrancheALoansMember_887C8CB8782E9F808DF8EB25193A0272" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_334DA74253B6E3383A25EB25193A27E6" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_60EBD3A59C2CE49AC6F8EB25193A0719" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_334DA74253B6E3383A25EB25193A27E6" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_SeniorNotesDue2025Member" xlink:label="loc_bah_SeniorNotesDue2025Member_8C3FDAB7079100CD75A6EB25193A9098" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_60EBD3A59C2CE49AC6F8EB25193A0719" xlink:to="loc_bah_SeniorNotesDue2025Member_8C3FDAB7079100CD75A6EB25193A9098" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="loc_us-gaap_VariableRateAxis_B78ACA8E8C2F7F640DAAEB25193B5E51" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_532F6840328A337A2896EB2519355D0D" xlink:to="loc_us-gaap_VariableRateAxis_B78ACA8E8C2F7F640DAAEB25193B5E51" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_DAE150409B05AC1B58B0EB25193BB519_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_B78ACA8E8C2F7F640DAAEB25193B5E51" xlink:to="loc_us-gaap_VariableRateDomain_DAE150409B05AC1B58B0EB25193BB519_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_DAE150409B05AC1B58B0EB25193BB519" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_B78ACA8E8C2F7F640DAAEB25193B5E51" xlink:to="loc_us-gaap_VariableRateDomain_DAE150409B05AC1B58B0EB25193BB519" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_OvernightFederalFundsRateMember" xlink:label="loc_bah_OvernightFederalFundsRateMember_3EB7110149EDF39032BBEB25193B8FB3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_DAE150409B05AC1B58B0EB25193BB519" xlink:to="loc_bah_OvernightFederalFundsRateMember_3EB7110149EDF39032BBEB25193B8FB3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_0A4F9AB8B6565282351FEB25193C4512" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_DAE150409B05AC1B58B0EB25193BB519" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_0A4F9AB8B6565282351FEB25193C4512" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_AlternativeBaseRateABRMember" xlink:label="loc_bah_AlternativeBaseRateABRMember_86BE931D74C8D5AB6775EB25193CE412" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_DAE150409B05AC1B58B0EB25193BB519" xlink:to="loc_bah_AlternativeBaseRateABRMember_86BE931D74C8D5AB6775EB25193CE412" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_C9411C6CA71CBEA789A3EB25193C3A63" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_532F6840328A337A2896EB2519355D0D" xlink:to="loc_srt_RangeAxis_C9411C6CA71CBEA789A3EB25193C3A63" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_67F3A72408A47D016CE6EB25193C85C2_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_C9411C6CA71CBEA789A3EB25193C3A63" xlink:to="loc_srt_RangeMember_67F3A72408A47D016CE6EB25193C85C2_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_67F3A72408A47D016CE6EB25193C85C2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_C9411C6CA71CBEA789A3EB25193C3A63" xlink:to="loc_srt_RangeMember_67F3A72408A47D016CE6EB25193C85C2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_3F14AF91B6C92CAC6B90EB25193C7F63" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_67F3A72408A47D016CE6EB25193C85C2" xlink:to="loc_srt_MinimumMember_3F14AF91B6C92CAC6B90EB25193C7F63" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_18E1F8CF5AC0E29AEB63EB25193D2B3C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_67F3A72408A47D016CE6EB25193C85C2" xlink:to="loc_srt_MaximumMember_18E1F8CF5AC0E29AEB63EB25193D2B3C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_FFBBE4614354EE431D11EB25193DC8C4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7D26ACE68AAF67FB3610EB25193DB185" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_FFBBE4614354EE431D11EB25193DC8C4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_BB510DB1C3230AD840DEEB25193D4CC8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7D26ACE68AAF67FB3610EB25193DB185" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_BB510DB1C3230AD840DEEB25193D4CC8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_DAD3F4B480E85DE6DE32EB25193D3263" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7D26ACE68AAF67FB3610EB25193DB185" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_DAD3F4B480E85DE6DE32EB25193D3263" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_LineOfCreditFacilityNumberOfDrawsAllowedOnFacility" xlink:label="loc_bah_LineOfCreditFacilityNumberOfDrawsAllowedOnFacility_37543F2E44B6CBB1BCE9EB25193E4CE0" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7D26ACE68AAF67FB3610EB25193DB185" xlink:to="loc_bah_LineOfCreditFacilityNumberOfDrawsAllowedOnFacility_37543F2E44B6CBB1BCE9EB25193E4CE0" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_LineOfCreditFacilityMinimumAmountPerDrawOnFacility" xlink:label="loc_bah_LineOfCreditFacilityMinimumAmountPerDrawOnFacility_11BF5FC78DAC2600500AEB25193EC508" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7D26ACE68AAF67FB3610EB25193DB185" xlink:to="loc_bah_LineOfCreditFacilityMinimumAmountPerDrawOnFacility_11BF5FC78DAC2600500AEB25193EC508" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_LongtermDebtMaximumExpandedLoanFacility" xlink:label="loc_bah_LongtermDebtMaximumExpandedLoanFacility_619E59A1716F63B5DDA6EB25193ED9D0" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7D26ACE68AAF67FB3610EB25193DB185" xlink:to="loc_bah_LongtermDebtMaximumExpandedLoanFacility_619E59A1716F63B5DDA6EB25193ED9D0" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DebtCovenantExpandedLoanPercentageofConsolidatedEBITDARequired" xlink:label="loc_bah_DebtCovenantExpandedLoanPercentageofConsolidatedEBITDARequired_6770649D8E8B9B049639EB25193ECE4B" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7D26ACE68AAF67FB3610EB25193DB185" xlink:to="loc_bah_DebtCovenantExpandedLoanPercentageofConsolidatedEBITDARequired_6770649D8E8B9B049639EB25193ECE4B" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DebtInstrumentNetSecuredLeverageRatioMaximum" xlink:label="loc_bah_DebtInstrumentNetSecuredLeverageRatioMaximum_E9A5B2E6428F5FD56AD7EB25193E72B0" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7D26ACE68AAF67FB3610EB25193DB185" xlink:to="loc_bah_DebtInstrumentNetSecuredLeverageRatioMaximum_E9A5B2E6428F5FD56AD7EB25193E72B0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityCommitmentFeePercentage" xlink:label="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_8B8BD0604BC64890640AEB25193F2FC4" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7D26ACE68AAF67FB3610EB25193DB185" xlink:to="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_8B8BD0604BC64890640AEB25193F2FC4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromLinesOfCredit" xlink:label="loc_us-gaap_ProceedsFromLinesOfCredit_FC1372EBC110FCD69812EB25193FF07F" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7D26ACE68AAF67FB3610EB25193DB185" xlink:to="loc_us-gaap_ProceedsFromLinesOfCredit_FC1372EBC110FCD69812EB25193FF07F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCredit" xlink:label="loc_us-gaap_LineOfCredit_831856751C7ED2CCEC14EB25193F4013" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7D26ACE68AAF67FB3610EB25193DB185" xlink:to="loc_us-gaap_LineOfCredit_831856751C7ED2CCEC14EB25193F4013" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DebtInstrumentQuarterlyPeriodicPaymentPercentagePrincipal" xlink:label="loc_bah_DebtInstrumentQuarterlyPeriodicPaymentPercentagePrincipal_685C5BA557C339530BFDEB25193F2E2E" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7D26ACE68AAF67FB3610EB25193DB185" xlink:to="loc_bah_DebtInstrumentQuarterlyPeriodicPaymentPercentagePrincipal_685C5BA557C339530BFDEB25193F2E2E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestPaid" xlink:label="loc_us-gaap_InterestPaid_20F7E3EBAC61D24D9DD3EB25193F6A9F" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7D26ACE68AAF67FB3610EB25193DB185" xlink:to="loc_us-gaap_InterestPaid_20F7E3EBAC61D24D9DD3EB25193F6A9F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_07986F60C7E8BFE04B96EB25193F6DAE" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7D26ACE68AAF67FB3610EB25193DB185" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_07986F60C7E8BFE04B96EB25193F6DAE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredFinanceCostsGross" xlink:label="loc_us-gaap_DeferredFinanceCostsGross_A473220055B4DA8FF447EB2519408D04" xlink:type="locator" />
    <link:definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7D26ACE68AAF67FB3610EB25193DB185" xlink:to="loc_us-gaap_DeferredFinanceCostsGross_A473220055B4DA8FF447EB2519408D04" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_DerivativeNotionalAmount" xlink:label="loc_invest_DerivativeNotionalAmount_5FE9669E3A4FC1621D08EB251940556C" xlink:type="locator" />
    <link:definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7D26ACE68AAF67FB3610EB25193DB185" xlink:to="loc_invest_DerivativeNotionalAmount_5FE9669E3A4FC1621D08EB251940556C" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DebtScheduleOfDebtDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_E4201A76E6B28805ED8BEA0F8E89C465" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_ADBE7B51405638EA05F9EA0F8E877F52" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_E4201A76E6B28805ED8BEA0F8E89C465" xlink:to="loc_us-gaap_DebtInstrumentTable_ADBE7B51405638EA05F9EA0F8E877F52" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_3B5B7DDDFDC2C95FECCFEA0F8E874A57" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_ADBE7B51405638EA05F9EA0F8E877F52" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_3B5B7DDDFDC2C95FECCFEA0F8E874A57" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_4EC33AB3F82518E81D3FEA0F8E87E7FF_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_3B5B7DDDFDC2C95FECCFEA0F8E874A57" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_4EC33AB3F82518E81D3FEA0F8E87E7FF_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_4EC33AB3F82518E81D3FEA0F8E87E7FF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_3B5B7DDDFDC2C95FECCFEA0F8E874A57" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_4EC33AB3F82518E81D3FEA0F8E87E7FF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SecuredDebtMember" xlink:label="loc_us-gaap_SecuredDebtMember_E1FD262237AC5611BEDAEA0F8E888789" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_4EC33AB3F82518E81D3FEA0F8E87E7FF" xlink:to="loc_us-gaap_SecuredDebtMember_E1FD262237AC5611BEDAEA0F8E888789" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SeniorNotesMember" xlink:label="loc_us-gaap_SeniorNotesMember_CA10FC98B79C45970ED2EA0F8E88C00B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_4EC33AB3F82518E81D3FEA0F8E87E7FF" xlink:to="loc_us-gaap_SeniorNotesMember_CA10FC98B79C45970ED2EA0F8E88C00B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_231810E7923497AD51ADEA0F8E884B1E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_ADBE7B51405638EA05F9EA0F8E877F52" xlink:to="loc_us-gaap_DebtInstrumentAxis_231810E7923497AD51ADEA0F8E884B1E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_2C6ECB29B97D98FD3D0EEA0F8E882479_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_231810E7923497AD51ADEA0F8E884B1E" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_2C6ECB29B97D98FD3D0EEA0F8E882479_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_2C6ECB29B97D98FD3D0EEA0F8E882479" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_231810E7923497AD51ADEA0F8E884B1E" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_2C6ECB29B97D98FD3D0EEA0F8E882479" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_TrancheALoansMember" xlink:label="loc_bah_TrancheALoansMember_040401C6B506C29D2360EA0F8E89BEC9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_2C6ECB29B97D98FD3D0EEA0F8E882479" xlink:to="loc_bah_TrancheALoansMember_040401C6B506C29D2360EA0F8E89BEC9" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_TrancheBLoansMember" xlink:label="loc_bah_TrancheBLoansMember_45A8D2C284E1A15CE353EA0F8E89BEFC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_2C6ECB29B97D98FD3D0EEA0F8E882479" xlink:to="loc_bah_TrancheBLoansMember_45A8D2C284E1A15CE353EA0F8E89BEFC" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_SeniorNotesDue2025Member" xlink:label="loc_bah_SeniorNotesDue2025Member_7E705C759E636EFBFE7FEA0F8E898725" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_2C6ECB29B97D98FD3D0EEA0F8E882479" xlink:to="loc_bah_SeniorNotesDue2025Member_7E705C759E636EFBFE7FEA0F8E898725" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtCurrentAndNoncurrentAbstract" xlink:label="loc_us-gaap_LongtermDebtCurrentAndNoncurrentAbstract_8370FB67C728DEC126F2EA0F8E8A9EF0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_E4201A76E6B28805ED8BEA0F8E89C465" xlink:to="loc_us-gaap_LongtermDebtCurrentAndNoncurrentAbstract_8370FB67C728DEC126F2EA0F8E8A9EF0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_244DFBA25365E5540415EA0F8E8A268B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtCurrentAndNoncurrentAbstract_8370FB67C728DEC126F2EA0F8E8A9EF0" xlink:to="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_244DFBA25365E5540415EA0F8E8A268B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_333BF1DCCD8F9B1B76ABEA0F8E8AECF9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtCurrentAndNoncurrentAbstract_8370FB67C728DEC126F2EA0F8E8A9EF0" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_333BF1DCCD8F9B1B76ABEA0F8E8AECF9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_8397C75EF06103371409EA0F8E8AB45C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtCurrentAndNoncurrentAbstract_8370FB67C728DEC126F2EA0F8E8A9EF0" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_8397C75EF06103371409EA0F8E8AB45C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermDebt" xlink:label="loc_us-gaap_LongTermDebt_11B40A85637D6E25FFB2EA0F8E8B7301" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtCurrentAndNoncurrentAbstract_8370FB67C728DEC126F2EA0F8E8A9EF0" xlink:to="loc_us-gaap_LongTermDebt_11B40A85637D6E25FFB2EA0F8E8B7301" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermDebtCurrent" xlink:label="loc_us-gaap_LongTermDebtCurrent_C25C4A4293201E3E9159EA0F8E8BC5A6" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtCurrentAndNoncurrentAbstract_8370FB67C728DEC126F2EA0F8E8A9EF0" xlink:to="loc_us-gaap_LongTermDebtCurrent_C25C4A4293201E3E9159EA0F8E8BC5A6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermDebtNoncurrent" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_EE3A7F75AE6BE9CC8071EA0F8E8B0FE8" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtCurrentAndNoncurrentAbstract_8370FB67C728DEC126F2EA0F8E8A9EF0" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_EE3A7F75AE6BE9CC8071EA0F8E8B0FE8" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DebtScheduleOfDetailOfInterestExpenseDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_634DC04584634BD11B25D58B5A4DC8AD" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_063CC765A3D1C251DE30D58B5A4B09BB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_634DC04584634BD11B25D58B5A4DC8AD" xlink:to="loc_us-gaap_DebtInstrumentTable_063CC765A3D1C251DE30D58B5A4B09BB" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_B14C353F866FDF10FFA1D58B5A4B309F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_063CC765A3D1C251DE30D58B5A4B09BB" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_B14C353F866FDF10FFA1D58B5A4B309F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_A23F5F00A2C723D3057DD58B5A4BFF09_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_B14C353F866FDF10FFA1D58B5A4B309F" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_A23F5F00A2C723D3057DD58B5A4BFF09_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_A23F5F00A2C723D3057DD58B5A4BFF09" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_B14C353F866FDF10FFA1D58B5A4B309F" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_A23F5F00A2C723D3057DD58B5A4BFF09" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SecuredDebtMember" xlink:label="loc_us-gaap_SecuredDebtMember_7F2541DF967B7A63CCADD58B5A4CFDC7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_A23F5F00A2C723D3057DD58B5A4BFF09" xlink:to="loc_us-gaap_SecuredDebtMember_7F2541DF967B7A63CCADD58B5A4CFDC7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_D98434FCF2020450AB0FD58B5A4C2AEE" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_A23F5F00A2C723D3057DD58B5A4BFF09" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_D98434FCF2020450AB0FD58B5A4C2AEE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SeniorNotesMember" xlink:label="loc_us-gaap_SeniorNotesMember_099B4712F4DC0929A6F4D58B5A4C6ED9" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_A23F5F00A2C723D3057DD58B5A4BFF09" xlink:to="loc_us-gaap_SeniorNotesMember_099B4712F4DC0929A6F4D58B5A4C6ED9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_7A4A7B40E776F1E4858DD58B5A4C5909" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_063CC765A3D1C251DE30D58B5A4B09BB" xlink:to="loc_us-gaap_DebtInstrumentAxis_7A4A7B40E776F1E4858DD58B5A4C5909" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_5B67880B47C58CE3DCA0D58B5A4D8A1F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_7A4A7B40E776F1E4858DD58B5A4C5909" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_5B67880B47C58CE3DCA0D58B5A4D8A1F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_5B67880B47C58CE3DCA0D58B5A4D8A1F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_7A4A7B40E776F1E4858DD58B5A4C5909" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_5B67880B47C58CE3DCA0D58B5A4D8A1F" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_TrancheALoansMember" xlink:label="loc_bah_TrancheALoansMember_A28D7FD93F28F285FFD4D58B5A4D754A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5B67880B47C58CE3DCA0D58B5A4D8A1F" xlink:to="loc_bah_TrancheALoansMember_A28D7FD93F28F285FFD4D58B5A4D754A" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_TrancheBLoansMember" xlink:label="loc_bah_TrancheBLoansMember_7444F521E730824DD8BAD58B5A4D0222" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5B67880B47C58CE3DCA0D58B5A4D8A1F" xlink:to="loc_bah_TrancheBLoansMember_7444F521E730824DD8BAD58B5A4D0222" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestExpenseDebt" xlink:label="loc_us-gaap_InterestExpenseDebt_5C174FE94530281648ABD58B5A4D96C1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_634DC04584634BD11B25D58B5A4DC8AD" xlink:to="loc_us-gaap_InterestExpenseDebt_5C174FE94530281648ABD58B5A4D96C1" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DeferredPaymentObligationInterestPayment" xlink:label="loc_bah_DeferredPaymentObligationInterestPayment_C438DDD95940AB23AF4BD58B5A4E5949" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_634DC04584634BD11B25D58B5A4DC8AD" xlink:to="loc_bah_DeferredPaymentObligationInterestPayment_C438DDD95940AB23AF4BD58B5A4E5949" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AmortizationOfFinancingCostsAndDiscounts" xlink:label="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_92962842B88F18A6AD7ED58B5A4EF192" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_634DC04584634BD11B25D58B5A4DC8AD" xlink:to="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_92962842B88F18A6AD7ED58B5A4EF192" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_InterestIncomeExpenseOther" xlink:label="loc_bah_InterestIncomeExpenseOther_003742876CF31BF176B0D61CA37E1F69" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_634DC04584634BD11B25D58B5A4DC8AD" xlink:to="loc_bah_InterestIncomeExpenseOther_003742876CF31BF176B0D61CA37E1F69" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestExpense" xlink:label="loc_us-gaap_InterestExpense_9F42408AF4F0F4BC8EAFD58B5A4EFEE7" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_634DC04584634BD11B25D58B5A4DC8AD" xlink:to="loc_us-gaap_InterestExpense_9F42408AF4F0F4BC8EAFD58B5A4EFEE7" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DebtScheduleOfFutureDebtPrincipalRepaymentsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_3F620CD5362D11A85488D58B5A59E728" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_3F5EA2908B9B133516E9D58B5A560DA3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3F620CD5362D11A85488D58B5A59E728" xlink:to="loc_us-gaap_DebtInstrumentTable_3F5EA2908B9B133516E9D58B5A560DA3" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_1091DE0937855C097904D58B5A564108" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_3F5EA2908B9B133516E9D58B5A560DA3" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_1091DE0937855C097904D58B5A564108" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_54DE4F1AF64917B0E1CFD58B5A57FADF_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_1091DE0937855C097904D58B5A564108" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_54DE4F1AF64917B0E1CFD58B5A57FADF_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_54DE4F1AF64917B0E1CFD58B5A57FADF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_1091DE0937855C097904D58B5A564108" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_54DE4F1AF64917B0E1CFD58B5A57FADF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SeniorNotesMember" xlink:label="loc_us-gaap_SeniorNotesMember_1D14CBA49442B98715D7D58B5A57C644" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_54DE4F1AF64917B0E1CFD58B5A57FADF" xlink:to="loc_us-gaap_SeniorNotesMember_1D14CBA49442B98715D7D58B5A57C644" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_AC374F675B2F1A3B8CAED58B5A57756A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_3F5EA2908B9B133516E9D58B5A560DA3" xlink:to="loc_us-gaap_DebtInstrumentAxis_AC374F675B2F1A3B8CAED58B5A57756A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_0DE95475F93D2176D3DDD58B5A58DFF9_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_AC374F675B2F1A3B8CAED58B5A57756A" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_0DE95475F93D2176D3DDD58B5A58DFF9_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_0DE95475F93D2176D3DDD58B5A58DFF9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_AC374F675B2F1A3B8CAED58B5A57756A" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_0DE95475F93D2176D3DDD58B5A58DFF9" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_TrancheALoansMember" xlink:label="loc_bah_TrancheALoansMember_D90AAF4316AC23C13309D58B5A587E9C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_0DE95475F93D2176D3DDD58B5A58DFF9" xlink:to="loc_bah_TrancheALoansMember_D90AAF4316AC23C13309D58B5A587E9C" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_TrancheBLoansMember" xlink:label="loc_bah_TrancheBLoansMember_9ADBC092EB203F95B616D58B5A595A6A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_0DE95475F93D2176D3DDD58B5A58DFF9" xlink:to="loc_bah_TrancheBLoansMember_9ADBC092EB203F95B616D58B5A595A6A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_55FA8F83A8082E5C0C22D58B5A597C55" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3F620CD5362D11A85488D58B5A59E728" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_55FA8F83A8082E5C0C22D58B5A597C55" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_7B453384D035CEABFEE2D58B5A5A92B5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3F620CD5362D11A85488D58B5A59E728" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_7B453384D035CEABFEE2D58B5A5A92B5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_888452CF564DA4CCF351D58B5A5A4D21" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3F620CD5362D11A85488D58B5A59E728" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_888452CF564DA4CCF351D58B5A5A4D21" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_496895A2551B7EDCBB4FD58B5A5ADA26" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3F620CD5362D11A85488D58B5A59E728" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_496895A2551B7EDCBB4FD58B5A5ADA26" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour_72D2865804D5482B396BD58B5A5A32C5" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3F620CD5362D11A85488D58B5A59E728" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour_72D2865804D5482B396BD58B5A5A32C5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive_293EEC41789323EF7814D58B5A5A7A7A" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3F620CD5362D11A85488D58B5A59E728" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive_293EEC41789323EF7814D58B5A5A7A7A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive_0BBDEC2CD37CDE3A201ED58B5A5BC529" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3F620CD5362D11A85488D58B5A59E728" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive_0BBDEC2CD37CDE3A201ED58B5A5BC529" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DebtTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DeferredPaymentObligation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DeferredPaymentObligationNarrativeDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DeferredPaymentObligationReconciliationOfPrincipalBalanceOfDpoToRecordedAmountDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DeferredPaymentObligationTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/Derivatives" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DerivativesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeLineItems" xlink:label="loc_us-gaap_DerivativeLineItems_DCD9829AB8EF9F0079EBEA0F8E14A376" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeTable" xlink:label="loc_us-gaap_DerivativeTable_361AB3B3C18900CC8CDFEA0F8E1091C0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_DCD9829AB8EF9F0079EBEA0F8E14A376" xlink:to="loc_us-gaap_DerivativeTable_361AB3B3C18900CC8CDFEA0F8E1091C0" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_FE024290941277492172EA0F8E10A0FA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_361AB3B3C18900CC8CDFEA0F8E1091C0" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_FE024290941277492172EA0F8E10A0FA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_33B7EFB61051E5C7B6F7EA0F8E1098AF_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_FE024290941277492172EA0F8E10A0FA" xlink:to="loc_us-gaap_HedgingRelationshipDomain_33B7EFB61051E5C7B6F7EA0F8E1098AF_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_33B7EFB61051E5C7B6F7EA0F8E1098AF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_FE024290941277492172EA0F8E10A0FA" xlink:to="loc_us-gaap_HedgingRelationshipDomain_33B7EFB61051E5C7B6F7EA0F8E1098AF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CashFlowHedgingMember" xlink:label="loc_us-gaap_CashFlowHedgingMember_4F4CFB3C31369A6BE03AEA0F8E111C6B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_33B7EFB61051E5C7B6F7EA0F8E1098AF" xlink:to="loc_us-gaap_CashFlowHedgingMember_4F4CFB3C31369A6BE03AEA0F8E111C6B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationAxis" xlink:label="loc_us-gaap_HedgingDesignationAxis_9EB8843800F0B656B571EA0F8E11155A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_361AB3B3C18900CC8CDFEA0F8E1091C0" xlink:to="loc_us-gaap_HedgingDesignationAxis_9EB8843800F0B656B571EA0F8E11155A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_D1D9096F9DB38939AA6AEA0F8E119E9B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_9EB8843800F0B656B571EA0F8E11155A" xlink:to="loc_us-gaap_HedgingDesignationDomain_D1D9096F9DB38939AA6AEA0F8E119E9B_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_D1D9096F9DB38939AA6AEA0F8E119E9B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_9EB8843800F0B656B571EA0F8E11155A" xlink:to="loc_us-gaap_HedgingDesignationDomain_D1D9096F9DB38939AA6AEA0F8E119E9B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DesignatedAsHedgingInstrumentMember" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_50BC72E9457F71E82C7EEA0F8E111E98" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_D1D9096F9DB38939AA6AEA0F8E119E9B" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_50BC72E9457F71E82C7EEA0F8E111E98" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_ADC5C53E05A711EDF374EA0F8E1263AB" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_361AB3B3C18900CC8CDFEA0F8E1091C0" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_ADC5C53E05A711EDF374EA0F8E1263AB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_6C5C16872EC94457D6EEEA0F8E125D5C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_ADC5C53E05A711EDF374EA0F8E1263AB" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_6C5C16872EC94457D6EEEA0F8E125D5C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_6C5C16872EC94457D6EEEA0F8E125D5C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_ADC5C53E05A711EDF374EA0F8E1263AB" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_6C5C16872EC94457D6EEEA0F8E125D5C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherCurrentAssetsMember" xlink:label="loc_us-gaap_OtherCurrentAssetsMember_D67CB997CFE70AA87514EA0F8E1278D8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_6C5C16872EC94457D6EEEA0F8E125D5C" xlink:to="loc_us-gaap_OtherCurrentAssetsMember_D67CB997CFE70AA87514EA0F8E1278D8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherNoncurrentAssetsMember" xlink:label="loc_us-gaap_OtherNoncurrentAssetsMember_FD5BD46FCD0661413197EA0F8E136046" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_6C5C16872EC94457D6EEEA0F8E125D5C" xlink:to="loc_us-gaap_OtherNoncurrentAssetsMember_FD5BD46FCD0661413197EA0F8E136046" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherCurrentLiabilitiesMember" xlink:label="loc_us-gaap_OtherCurrentLiabilitiesMember_D2D909EA23E1E0EFC078EA0F8E13BF46" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_6C5C16872EC94457D6EEEA0F8E125D5C" xlink:to="loc_us-gaap_OtherCurrentLiabilitiesMember_D2D909EA23E1E0EFC078EA0F8E13BF46" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherNoncurrentLiabilitiesMember" xlink:label="loc_us-gaap_OtherNoncurrentLiabilitiesMember_B9F04E4C90260F4DF806EA0F8E13855D" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_6C5C16872EC94457D6EEEA0F8E125D5C" xlink:to="loc_us-gaap_OtherNoncurrentLiabilitiesMember_B9F04E4C90260F4DF806EA0F8E13855D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_B9A5F5643CE1C827F97AEA0F8E1310B4" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_361AB3B3C18900CC8CDFEA0F8E1091C0" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_B9A5F5643CE1C827F97AEA0F8E1310B4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_3CC6805CDB434DCF79ADEA0F8E133136_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_B9A5F5643CE1C827F97AEA0F8E1310B4" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_3CC6805CDB434DCF79ADEA0F8E133136_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_3CC6805CDB434DCF79ADEA0F8E133136" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_B9A5F5643CE1C827F97AEA0F8E1310B4" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_3CC6805CDB434DCF79ADEA0F8E133136" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_ForwardStartingFloatingToFixedInterestRateSwapMember" xlink:label="loc_bah_ForwardStartingFloatingToFixedInterestRateSwapMember_E773BA275D21AC6312FBEA0F8E13E717" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_3CC6805CDB434DCF79ADEA0F8E133136" xlink:to="loc_bah_ForwardStartingFloatingToFixedInterestRateSwapMember_E773BA275D21AC6312FBEA0F8E13E717" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_3824336400994C88D702EA0F8E14092A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_3CC6805CDB434DCF79ADEA0F8E133136" xlink:to="loc_us-gaap_InterestRateSwapMember_3824336400994C88D702EA0F8E14092A" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DerivativesNumberOfAgreementsEnteredIntoDuringThePeriod" xlink:label="loc_bah_DerivativesNumberOfAgreementsEnteredIntoDuringThePeriod_C432BA93AC7BF18E302EEA0F8E14EA38" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_DCD9829AB8EF9F0079EBEA0F8E14A376" xlink:to="loc_bah_DerivativesNumberOfAgreementsEnteredIntoDuringThePeriod_C432BA93AC7BF18E302EEA0F8E14EA38" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_DerivativeNotionalAmount" xlink:label="loc_invest_DerivativeNotionalAmount_B5B6F0DE5035D31482DDEA0F8E14D9EF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_DCD9829AB8EF9F0079EBEA0F8E14A376" xlink:to="loc_invest_DerivativeNotionalAmount_B5B6F0DE5035D31482DDEA0F8E14D9EF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsInHedgesAssetsAtFairValue" xlink:label="loc_us-gaap_DerivativeInstrumentsInHedgesAssetsAtFairValue_35E9C484D1D00B6794FAEA0F8E15B93F" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_DCD9829AB8EF9F0079EBEA0F8E14A376" xlink:to="loc_us-gaap_DerivativeInstrumentsInHedgesAssetsAtFairValue_35E9C484D1D00B6794FAEA0F8E15B93F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsInHedgesLiabilitiesAtFairValue" xlink:label="loc_us-gaap_DerivativeInstrumentsInHedgesLiabilitiesAtFairValue_DD4F4217D6D122AA2419EA0F8E150326" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_DCD9829AB8EF9F0079EBEA0F8E14A376" xlink:to="loc_us-gaap_DerivativeInstrumentsInHedgesLiabilitiesAtFairValue_DD4F4217D6D122AA2419EA0F8E150326" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet" xlink:label="loc_us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet_68E7450830DF24CF2089EA0F8E15A0F3" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_DCD9829AB8EF9F0079EBEA0F8E14A376" xlink:to="loc_us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet_68E7450830DF24CF2089EA0F8E15A0F3" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DerivativesScheduleOfEffectOfDerivativesOnFinancialStatementsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_0026361178FC5CA96A48D58B5A2CDFBC" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_5B7D16F18E47778D8FC9D58B5A2905CB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_0026361178FC5CA96A48D58B5A2CDFBC" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_5B7D16F18E47778D8FC9D58B5A2905CB" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_82914F0BA6366DD9AD41D58B5A297CD9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_5B7D16F18E47778D8FC9D58B5A2905CB" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_82914F0BA6366DD9AD41D58B5A297CD9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_8B95EDE82E430CEB5572D58B5A2A5EEC_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_82914F0BA6366DD9AD41D58B5A297CD9" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_8B95EDE82E430CEB5572D58B5A2A5EEC_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_8B95EDE82E430CEB5572D58B5A2A5EEC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_82914F0BA6366DD9AD41D58B5A297CD9" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_8B95EDE82E430CEB5572D58B5A2A5EEC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_3DBD8604FB64DF2397E2D58B5A2A1644" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_8B95EDE82E430CEB5572D58B5A2A5EEC" xlink:to="loc_us-gaap_InterestRateSwapMember_3DBD8604FB64DF2397E2D58B5A2A1644" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationAxis" xlink:label="loc_us-gaap_HedgingDesignationAxis_2334BC0B4A74D31E427ED58B5A2A751D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_5B7D16F18E47778D8FC9D58B5A2905CB" xlink:to="loc_us-gaap_HedgingDesignationAxis_2334BC0B4A74D31E427ED58B5A2A751D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_7EF65FD2B5E368507D3CD58B5A2BE09F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_2334BC0B4A74D31E427ED58B5A2A751D" xlink:to="loc_us-gaap_HedgingDesignationDomain_7EF65FD2B5E368507D3CD58B5A2BE09F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_7EF65FD2B5E368507D3CD58B5A2BE09F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_2334BC0B4A74D31E427ED58B5A2A751D" xlink:to="loc_us-gaap_HedgingDesignationDomain_7EF65FD2B5E368507D3CD58B5A2BE09F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DesignatedAsHedgingInstrumentMember" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_6112AA050D4CC3BCD860D58B5A2B13E5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_7EF65FD2B5E368507D3CD58B5A2BE09F" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_6112AA050D4CC3BCD860D58B5A2B13E5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_81E69E5896973C589FE5D58B5A2B629F" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_5B7D16F18E47778D8FC9D58B5A2905CB" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_81E69E5896973C589FE5D58B5A2B629F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_627ABEF0C44D66D060D6D58B5A2BB8CE_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_81E69E5896973C589FE5D58B5A2B629F" xlink:to="loc_us-gaap_HedgingRelationshipDomain_627ABEF0C44D66D060D6D58B5A2BB8CE_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_627ABEF0C44D66D060D6D58B5A2BB8CE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_81E69E5896973C589FE5D58B5A2B629F" xlink:to="loc_us-gaap_HedgingRelationshipDomain_627ABEF0C44D66D060D6D58B5A2BB8CE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CashFlowHedgingMember" xlink:label="loc_us-gaap_CashFlowHedgingMember_C805AE5E61A1FE5277F3D58B5A2C66CD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_627ABEF0C44D66D060D6D58B5A2BB8CE" xlink:to="loc_us-gaap_CashFlowHedgingMember_C805AE5E61A1FE5277F3D58B5A2C66CD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax_8DBD5AF45CECC83E67C2D58B5A2C7CF4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_0026361178FC5CA96A48D58B5A2CDFBC" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax_8DBD5AF45CECC83E67C2D58B5A2C7CF4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet" xlink:label="loc_us-gaap_InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet_C6BE10B3526C0C021243D58B5A2DAF80" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_0026361178FC5CA96A48D58B5A2CDFBC" xlink:to="loc_us-gaap_InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet_C6BE10B3526C0C021243D58B5A2DAF80" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestExpense" xlink:label="loc_us-gaap_InterestExpense_95FFDF76176E008B2988D58B5A2D01A8" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_0026361178FC5CA96A48D58B5A2CDFBC" xlink:to="loc_us-gaap_InterestExpense_95FFDF76176E008B2988D58B5A2D01A8" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DerivativesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DocumentAndEntityInformation" xlink:type="extended">
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityInformationLineItems" xlink:label="loc_dei_EntityInformationLineItems_FE5FF129FEBE0C4A8BEEE66A54489C0E" xlink:type="locator" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntitiesTable" xlink:label="loc_dei_EntitiesTable_13E247E78F02210823A1E66A544331E9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_EntityInformationLineItems_FE5FF129FEBE0C4A8BEEE66A54489C0E" xlink:to="loc_dei_EntitiesTable_13E247E78F02210823A1E66A544331E9" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_1ECB37F58D3F8D895773E66A54440B04" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_EntitiesTable_13E247E78F02210823A1E66A544331E9" xlink:to="loc_us-gaap_StatementClassOfStockAxis_1ECB37F58D3F8D895773E66A54440B04" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_CA5C94330B0519A1E606E66A544498FE_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_1ECB37F58D3F8D895773E66A54440B04" xlink:to="loc_us-gaap_ClassOfStockDomain_CA5C94330B0519A1E606E66A544498FE_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_CA5C94330B0519A1E606E66A544498FE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_1ECB37F58D3F8D895773E66A54440B04" xlink:to="loc_us-gaap_ClassOfStockDomain_CA5C94330B0519A1E606E66A544498FE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonClassAMember" xlink:label="loc_us-gaap_CommonClassAMember_A39216D01135444D8269E66A5445F08B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_CA5C94330B0519A1E606E66A544498FE" xlink:to="loc_us-gaap_CommonClassAMember_A39216D01135444D8269E66A5445F08B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonClassBMember" xlink:label="loc_us-gaap_CommonClassBMember_F6435EC351ABC8997D23E66A54476559" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_CA5C94330B0519A1E606E66A544498FE" xlink:to="loc_us-gaap_CommonClassBMember_F6435EC351ABC8997D23E66A54476559" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonClassCMember" xlink:label="loc_us-gaap_CommonClassCMember_A3A358436365DC90ECACE66A54480A9C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_CA5C94330B0519A1E606E66A544498FE" xlink:to="loc_us-gaap_CommonClassCMember_A3A358436365DC90ECACE66A54480A9C" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_CommonClassEMember" xlink:label="loc_bah_CommonClassEMember_9936FDE675E8365962B3E66A5448C2EF" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_CA5C94330B0519A1E606E66A544498FE" xlink:to="loc_bah_CommonClassEMember_9936FDE675E8365962B3E66A5448C2EF" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityRegistrantName" xlink:label="loc_dei_EntityRegistrantName_17C6D2A783636C916E31E66A5448B4E3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_FE5FF129FEBE0C4A8BEEE66A54489C0E" xlink:to="loc_dei_EntityRegistrantName_17C6D2A783636C916E31E66A5448B4E3" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityCentralIndexKey" xlink:label="loc_dei_EntityCentralIndexKey_E24972ACE0F078622272E66A5448DBA5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_FE5FF129FEBE0C4A8BEEE66A54489C0E" xlink:to="loc_dei_EntityCentralIndexKey_E24972ACE0F078622272E66A5448DBA5" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_DocumentType" xlink:label="loc_dei_DocumentType_F802F98F5D908A4DEC4DE66A5449C1A0" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_FE5FF129FEBE0C4A8BEEE66A54489C0E" xlink:to="loc_dei_DocumentType_F802F98F5D908A4DEC4DE66A5449C1A0" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_DocumentPeriodEndDate" xlink:label="loc_dei_DocumentPeriodEndDate_9B646BD013160EFE8CABE66A5449EA36" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_FE5FF129FEBE0C4A8BEEE66A54489C0E" xlink:to="loc_dei_DocumentPeriodEndDate_9B646BD013160EFE8CABE66A5449EA36" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_AmendmentFlag" xlink:label="loc_dei_AmendmentFlag_7CB63BD9E05D008A496DE66A5449CEAB" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_FE5FF129FEBE0C4A8BEEE66A54489C0E" xlink:to="loc_dei_AmendmentFlag_7CB63BD9E05D008A496DE66A5449CEAB" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_DocumentFiscalYearFocus" xlink:label="loc_dei_DocumentFiscalYearFocus_6F7ED9A24EA7E28029B5E66A5449DA8D" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_FE5FF129FEBE0C4A8BEEE66A54489C0E" xlink:to="loc_dei_DocumentFiscalYearFocus_6F7ED9A24EA7E28029B5E66A5449DA8D" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_DocumentFiscalPeriodFocus" xlink:label="loc_dei_DocumentFiscalPeriodFocus_306B2BACE327006610A1E66A54493B83" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_FE5FF129FEBE0C4A8BEEE66A54489C0E" xlink:to="loc_dei_DocumentFiscalPeriodFocus_306B2BACE327006610A1E66A54493B83" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_CurrentFiscalYearEndDate" xlink:label="loc_dei_CurrentFiscalYearEndDate_AAE2CE88AB96F1534627E66A54490089" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_FE5FF129FEBE0C4A8BEEE66A54489C0E" xlink:to="loc_dei_CurrentFiscalYearEndDate_AAE2CE88AB96F1534627E66A54490089" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityFilerCategory" xlink:label="loc_dei_EntityFilerCategory_42FEBCD158D6CE9742A8E66A544AB48D" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_FE5FF129FEBE0C4A8BEEE66A54489C0E" xlink:to="loc_dei_EntityFilerCategory_42FEBCD158D6CE9742A8E66A544AB48D" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityWellKnownSeasonedIssuer" xlink:label="loc_dei_EntityWellKnownSeasonedIssuer_71D8F9742925129A07BBE66A544A15FF" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_FE5FF129FEBE0C4A8BEEE66A54489C0E" xlink:to="loc_dei_EntityWellKnownSeasonedIssuer_71D8F9742925129A07BBE66A544A15FF" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityVoluntaryFilers" xlink:label="loc_dei_EntityVoluntaryFilers_84C361AA36A1B0AEDC77E66A544AD708" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_FE5FF129FEBE0C4A8BEEE66A54489C0E" xlink:to="loc_dei_EntityVoluntaryFilers_84C361AA36A1B0AEDC77E66A544AD708" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityCurrentReportingStatus" xlink:label="loc_dei_EntityCurrentReportingStatus_B1DE9E7EEAD7F811B765E66A544A70E8" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_FE5FF129FEBE0C4A8BEEE66A54489C0E" xlink:to="loc_dei_EntityCurrentReportingStatus_B1DE9E7EEAD7F811B765E66A544A70E8" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntitySmallBusiness" xlink:label="loc_dei_EntitySmallBusiness_35F41CA842B0B7301FA3E66A544A4748" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_FE5FF129FEBE0C4A8BEEE66A54489C0E" xlink:to="loc_dei_EntitySmallBusiness_35F41CA842B0B7301FA3E66A544A4748" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityEmergingGrowthCompany" xlink:label="loc_dei_EntityEmergingGrowthCompany_FED6DFC4F2FFC360FDA9E66A544AF931" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_FE5FF129FEBE0C4A8BEEE66A54489C0E" xlink:to="loc_dei_EntityEmergingGrowthCompany_FED6DFC4F2FFC360FDA9E66A544AF931" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityShellCompany" xlink:label="loc_dei_EntityShellCompany_6F53204833ABE74047ADE66A5501383B" xlink:type="locator" />
    <link:definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_FE5FF129FEBE0C4A8BEEE66A54489C0E" xlink:to="loc_dei_EntityShellCompany_6F53204833ABE74047ADE66A5501383B" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityPublicFloat" xlink:label="loc_dei_EntityPublicFloat_C29728ADBD6DBC9A00E6E66A544BB5A5" xlink:type="locator" />
    <link:definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_FE5FF129FEBE0C4A8BEEE66A54489C0E" xlink:to="loc_dei_EntityPublicFloat_C29728ADBD6DBC9A00E6E66A544BB5A5" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityCommonStockSharesOutstanding" xlink:label="loc_dei_EntityCommonStockSharesOutstanding_2DC8AF38B41E5D0A1483E66A544B9B95" xlink:type="locator" />
    <link:definitionArc order="17" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_FE5FF129FEBE0C4A8BEEE66A54489C0E" xlink:to="loc_dei_EntityCommonStockSharesOutstanding_2DC8AF38B41E5D0A1483E66A544B9B95" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EarningsPerShare" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EarningsPerShareDetails" xlink:type="extended">
    <link:loc xlink:href="bah-20190331.xsd#bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems" xlink:label="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_3D6A0F20A088CB911D1FEA0F8F16C035" xlink:type="locator" />
    <link:loc xlink:href="bah-20190331.xsd#bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassTable" xlink:label="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassTable_66F92D2E0B6F9DA234F0EA0F8F135A6E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_3D6A0F20A088CB911D1FEA0F8F16C035" xlink:to="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassTable_66F92D2E0B6F9DA234F0EA0F8F135A6E" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_926AE64B33B15C409DC8EA0F8F1389FB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassTable_66F92D2E0B6F9DA234F0EA0F8F135A6E" xlink:to="loc_us-gaap_StatementClassOfStockAxis_926AE64B33B15C409DC8EA0F8F1389FB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_79B72C4F71EA26A9118FEA0F8F14AB4B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_926AE64B33B15C409DC8EA0F8F1389FB" xlink:to="loc_us-gaap_ClassOfStockDomain_79B72C4F71EA26A9118FEA0F8F14AB4B_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_79B72C4F71EA26A9118FEA0F8F14AB4B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_926AE64B33B15C409DC8EA0F8F1389FB" xlink:to="loc_us-gaap_ClassOfStockDomain_79B72C4F71EA26A9118FEA0F8F14AB4B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonClassAMember" xlink:label="loc_us-gaap_CommonClassAMember_58D3FA9CE372A51E78E1EA0F8F1401C0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_79B72C4F71EA26A9118FEA0F8F14AB4B" xlink:to="loc_us-gaap_CommonClassAMember_58D3FA9CE372A51E78E1EA0F8F1401C0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_9923EFDF2A131EFDD87DEA0F8F15A9F8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassTable_66F92D2E0B6F9DA234F0EA0F8F135A6E" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_9923EFDF2A131EFDD87DEA0F8F15A9F8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_21ACFD215C2955C59698EA0F8F15EFE8_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_9923EFDF2A131EFDD87DEA0F8F15A9F8" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_21ACFD215C2955C59698EA0F8F15EFE8_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_21ACFD215C2955C59698EA0F8F15EFE8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_9923EFDF2A131EFDD87DEA0F8F15A9F8" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_21ACFD215C2955C59698EA0F8F15EFE8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_5B6FAB90EAD2A3AA62CFEA0F8F152B04" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_21ACFD215C2955C59698EA0F8F15EFE8" xlink:to="loc_us-gaap_RestrictedStockMember_5B6FAB90EAD2A3AA62CFEA0F8F152B04" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_71AD28A37B9CAE7332F7EA0F8F163E46" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_21ACFD215C2955C59698EA0F8F15EFE8" xlink:to="loc_us-gaap_EmployeeStockOptionMember_71AD28A37B9CAE7332F7EA0F8F163E46" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_UndistributedEarnings" xlink:label="loc_us-gaap_UndistributedEarnings_8A1BA576B2A06EAA19B7EA0F8F168D2A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_3D6A0F20A088CB911D1FEA0F8F16C035" xlink:to="loc_us-gaap_UndistributedEarnings_8A1BA576B2A06EAA19B7EA0F8F168D2A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_B0B1E5ADAEEA8E7B31DBEA0F8F16186C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_3D6A0F20A088CB911D1FEA0F8F16C035" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_B0B1E5ADAEEA8E7B31DBEA0F8F16186C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_UndistributedEarningsDiluted" xlink:label="loc_us-gaap_UndistributedEarningsDiluted_9C242D7E690DD33C1EDAEA0F8F177F14" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_3D6A0F20A088CB911D1FEA0F8F16C035" xlink:to="loc_us-gaap_UndistributedEarningsDiluted_9C242D7E690DD33C1EDAEA0F8F177F14" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" xlink:label="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment_503A6FD31D0A927F810EEA0F8F17923D" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_3D6A0F20A088CB911D1FEA0F8F16C035" xlink:to="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment_503A6FD31D0A927F810EEA0F8F17923D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_A4067D8E782C891063D5EA0F8F1777FE" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_3D6A0F20A088CB911D1FEA0F8F16C035" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_A4067D8E782C891063D5EA0F8F1777FE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EarningsPerShareBasicAndDilutedAbstract" xlink:label="loc_us-gaap_EarningsPerShareBasicAndDilutedAbstract_CB10447732242853C1D5EA3CF41EC33A" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_3D6A0F20A088CB911D1FEA0F8F16C035" xlink:to="loc_us-gaap_EarningsPerShareBasicAndDilutedAbstract_CB10447732242853C1D5EA3CF41EC33A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EarningsPerShareBasic" xlink:label="loc_us-gaap_EarningsPerShareBasic_360B636B9F265B63B202EA0F8F17CD1A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAndDilutedAbstract_CB10447732242853C1D5EA3CF41EC33A" xlink:to="loc_us-gaap_EarningsPerShareBasic_360B636B9F265B63B202EA0F8F17CD1A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EarningsPerShareDiluted" xlink:label="loc_us-gaap_EarningsPerShareDiluted_2864D16FD639B6A49115EA0F8F17B4D6" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAndDilutedAbstract_CB10447732242853C1D5EA3CF41EC33A" xlink:to="loc_us-gaap_EarningsPerShareDiluted_2864D16FD639B6A49115EA0F8F17B4D6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncrementalCommonSharesAttributableToParticipatingNonvestedSharesWithNonForfeitableDividendRights" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToParticipatingNonvestedSharesWithNonForfeitableDividendRights_E8A3B0ECCEECC11E532BEA0F8F175BA0" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_3D6A0F20A088CB911D1FEA0F8F16C035" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToParticipatingNonvestedSharesWithNonForfeitableDividendRights_E8A3B0ECCEECC11E532BEA0F8F175BA0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaymentsOfDividends" xlink:label="loc_us-gaap_PaymentsOfDividends_A59A06801030790FF9C6EA0F8F188D95" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_3D6A0F20A088CB911D1FEA0F8F16C035" xlink:to="loc_us-gaap_PaymentsOfDividends_A59A06801030790FF9C6EA0F8F188D95" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic" xlink:label="loc_us-gaap_UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic_BF5C6335A3F75B6F1A70EA0F8F18D11D" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_3D6A0F20A088CB911D1FEA0F8F16C035" xlink:to="loc_us-gaap_UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic_BF5C6335A3F75B6F1A70EA0F8F18D11D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted" xlink:label="loc_us-gaap_UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted_A42C8A76817D9E808861EA0F8F18F75F" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_3D6A0F20A088CB911D1FEA0F8F16C035" xlink:to="loc_us-gaap_UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted_A42C8A76817D9E808861EA0F8F18F75F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_77ECE62B3B6EC2725CD6EA0F8F194E3F" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_3D6A0F20A088CB911D1FEA0F8F16C035" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_77ECE62B3B6EC2725CD6EA0F8F194E3F" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EarningsPerShareTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EmployeeBenefitPlans" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EmployeeBenefitPlansAccumulatedOtherComprehensiveIncomeDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EmployeeBenefitPlansChangeInBenefitObligationAndChangeInPlanAssetsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_C020656546AFD13CC877EA7A4CE89B13" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_9535BE566847454487B6EA7A4CE63638" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_C020656546AFD13CC877EA7A4CE89B13" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_9535BE566847454487B6EA7A4CE63638" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanNameAxis" xlink:label="loc_us-gaap_RetirementPlanNameAxis_4129B4C4CF5AC87248C3EA7A4CE657ED" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_9535BE566847454487B6EA7A4CE63638" xlink:to="loc_us-gaap_RetirementPlanNameAxis_4129B4C4CF5AC87248C3EA7A4CE657ED" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanNameDomain" xlink:label="loc_us-gaap_RetirementPlanNameDomain_1593D464F689293EFFAEEA7A4CE6B2FD_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanNameAxis_4129B4C4CF5AC87248C3EA7A4CE657ED" xlink:to="loc_us-gaap_RetirementPlanNameDomain_1593D464F689293EFFAEEA7A4CE6B2FD_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanNameDomain" xlink:label="loc_us-gaap_RetirementPlanNameDomain_1593D464F689293EFFAEEA7A4CE6B2FD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanNameAxis_4129B4C4CF5AC87248C3EA7A4CE657ED" xlink:to="loc_us-gaap_RetirementPlanNameDomain_1593D464F689293EFFAEEA7A4CE6B2FD" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_OfficerMedicalPlanMember" xlink:label="loc_bah_OfficerMedicalPlanMember_270912ABCE8FC952162EEA7A4CE71408" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanNameDomain_1593D464F689293EFFAEEA7A4CE6B2FD" xlink:to="loc_bah_OfficerMedicalPlanMember_270912ABCE8FC952162EEA7A4CE71408" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_RetiredOfficersBonusPlanandRetiredVicePresidentBonusPlanMember" xlink:label="loc_bah_RetiredOfficersBonusPlanandRetiredVicePresidentBonusPlanMember_F0D9D9BEB271E3A4CBECEA7A4CE7BA3A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanNameDomain_1593D464F689293EFFAEEA7A4CE6B2FD" xlink:to="loc_bah_RetiredOfficersBonusPlanandRetiredVicePresidentBonusPlanMember_F0D9D9BEB271E3A4CBECEA7A4CE7BA3A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanTypeAxis" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_DF7532640F493C7081BFEA7A4CE77718" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_9535BE566847454487B6EA7A4CE63638" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_DF7532640F493C7081BFEA7A4CE77718" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_CF87F34B253D1D64F614EA7A4CE7181E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_DF7532640F493C7081BFEA7A4CE77718" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_CF87F34B253D1D64F614EA7A4CE7181E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_CF87F34B253D1D64F614EA7A4CE7181E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_DF7532640F493C7081BFEA7A4CE77718" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_CF87F34B253D1D64F614EA7A4CE7181E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_EFAE7B563188E6D4A293EA7A4CE823A1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_CF87F34B253D1D64F614EA7A4CE7181E" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_EFAE7B563188E6D4A293EA7A4CE823A1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward" xlink:label="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_80DDEF580033406DDFE9EA7A4CE84D23" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_C020656546AFD13CC877EA7A4CE89B13" xlink:to="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_80DDEF580033406DDFE9EA7A4CE84D23" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanBenefitObligation" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligation_80B16344B08B2533182EEA7A4CEEC86D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_80DDEF580033406DDFE9EA7A4CE84D23" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligation_80B16344B08B2533182EEA7A4CEEC86D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanServiceCost" xlink:label="loc_us-gaap_DefinedBenefitPlanServiceCost_488B8EC80EE5C04DBC9EEA7A4CEE5B18" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_80DDEF580033406DDFE9EA7A4CE84D23" xlink:to="loc_us-gaap_DefinedBenefitPlanServiceCost_488B8EC80EE5C04DBC9EEA7A4CEE5B18" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanInterestCost" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_045F9C480469B8625D35EA7A4CEE343F" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_80DDEF580033406DDFE9EA7A4CE84D23" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_045F9C480469B8625D35EA7A4CEE343F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanActuarialGainLoss" xlink:label="loc_us-gaap_DefinedBenefitPlanActuarialGainLoss_60AD80D6A4D0F395459DEA7A4CEFD837" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_80DDEF580033406DDFE9EA7A4CE84D23" xlink:to="loc_us-gaap_DefinedBenefitPlanActuarialGainLoss_60AD80D6A4D0F395459DEA7A4CEFD837" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid_CD2CDD78B5B2E74E7671EA7A4CEF9A09" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_80DDEF580033406DDFE9EA7A4CE84D23" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid_CD2CDD78B5B2E74E7671EA7A4CEF9A09" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward" xlink:label="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_2BFED9427F2560FDC7D4EA7A4CEF1A70" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_C020656546AFD13CC877EA7A4CE89B13" xlink:to="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_2BFED9427F2560FDC7D4EA7A4CEF1A70" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" xlink:label="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_6E81F59AFA07BAADF51BEA7A4CEFC561" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_2BFED9427F2560FDC7D4EA7A4CEF1A70" xlink:to="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_6E81F59AFA07BAADF51BEA7A4CEFC561" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanContributionsByEmployer" xlink:label="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_B3CF8AB915F4E76D7763EA7A4CF045F7" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_2BFED9427F2560FDC7D4EA7A4CEF1A70" xlink:to="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_B3CF8AB915F4E76D7763EA7A4CF045F7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid" xlink:label="loc_us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid_CC95C0D0AE1594936896EA7A4CF0CB79" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_2BFED9427F2560FDC7D4EA7A4CEF1A70" xlink:to="loc_us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid_CC95C0D0AE1594936896EA7A4CF0CB79" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanFundedStatusOfPlan" xlink:label="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_71E32F143C416D600FA1EA7A4CF114E6" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_C020656546AFD13CC877EA7A4CE89B13" xlink:to="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_71E32F143C416D600FA1EA7A4CF114E6" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EmployeeBenefitPlansComponentsOfNetPostretirementMedicalExpenseDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_04200B1CFE0852A9BBC1753564B446DC" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_C75A963BB6CE59D0A59FFF554BE8E000" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_04200B1CFE0852A9BBC1753564B446DC" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_C75A963BB6CE59D0A59FFF554BE8E000" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanNameAxis" xlink:label="loc_us-gaap_RetirementPlanNameAxis_65BCF862D6A0565285629FDA82C57B7E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_C75A963BB6CE59D0A59FFF554BE8E000" xlink:to="loc_us-gaap_RetirementPlanNameAxis_65BCF862D6A0565285629FDA82C57B7E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanNameDomain" xlink:label="loc_us-gaap_RetirementPlanNameDomain_9E1D01A9756E0BA4DC11E666C27A5236_3A03FFEE806B57A6BB951B08A10A2E36" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanNameAxis_65BCF862D6A0565285629FDA82C57B7E" xlink:to="loc_us-gaap_RetirementPlanNameDomain_9E1D01A9756E0BA4DC11E666C27A5236_3A03FFEE806B57A6BB951B08A10A2E36" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanNameDomain" xlink:label="loc_us-gaap_RetirementPlanNameDomain_DD0C5ED42D025EC09611FECF9E2AD7EB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanNameAxis_65BCF862D6A0565285629FDA82C57B7E" xlink:to="loc_us-gaap_RetirementPlanNameDomain_DD0C5ED42D025EC09611FECF9E2AD7EB" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_OfficerMedicalPlanMember" xlink:label="loc_bah_OfficerMedicalPlanMember_A6BE261223425FDEA5A8DF51563A281F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanNameDomain_DD0C5ED42D025EC09611FECF9E2AD7EB" xlink:to="loc_bah_OfficerMedicalPlanMember_A6BE261223425FDEA5A8DF51563A281F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanTypeAxis" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_0D4A54204B4A54FC94FA9BFC0FBF474C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_C75A963BB6CE59D0A59FFF554BE8E000" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_0D4A54204B4A54FC94FA9BFC0FBF474C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_ED4876A824A3637CAC31E666C27B92E3_3A03FFEE806B57A6BB951B08A10A2E36" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_0D4A54204B4A54FC94FA9BFC0FBF474C" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_ED4876A824A3637CAC31E666C27B92E3_3A03FFEE806B57A6BB951B08A10A2E36" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_AC7931FFBF315EEFB24ADDBA4AB11241" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_0D4A54204B4A54FC94FA9BFC0FBF474C" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_AC7931FFBF315EEFB24ADDBA4AB11241" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_5F95C080DF0B53E28B6B473F246F4CB9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_AC7931FFBF315EEFB24ADDBA4AB11241" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_5F95C080DF0B53E28B6B473F246F4CB9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanServiceCost" xlink:label="loc_us-gaap_DefinedBenefitPlanServiceCost_922F06ACD7725E94A088F07B0FD47F9D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_04200B1CFE0852A9BBC1753564B446DC" xlink:to="loc_us-gaap_DefinedBenefitPlanServiceCost_922F06ACD7725E94A088F07B0FD47F9D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanInterestCost" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_1D14CE4DBD0751BAA049EB06FA75F25A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_04200B1CFE0852A9BBC1753564B446DC" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_1D14CE4DBD0751BAA049EB06FA75F25A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_CBD4E0141BBB5F72BCCB1E864F467856" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_04200B1CFE0852A9BBC1753564B446DC" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_CBD4E0141BBB5F72BCCB1E864F467856" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_FEB0818431BE5734A9FB56873098D826" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_04200B1CFE0852A9BBC1753564B446DC" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_FEB0818431BE5734A9FB56873098D826" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EmployeeBenefitPlansFutureBenefitPaymentsDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EmployeeBenefitPlansHealthcareCostTrendRatesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_E47FEC470FEA95E8587AD589CC730245" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_507540C7A188D3C9B61BD589CC6FCA7E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_E47FEC470FEA95E8587AD589CC730245" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_507540C7A188D3C9B61BD589CC6FCA7E" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanNameAxis" xlink:label="loc_us-gaap_RetirementPlanNameAxis_CF7CDDB6D2F4423246AAD589CC702193" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_507540C7A188D3C9B61BD589CC6FCA7E" xlink:to="loc_us-gaap_RetirementPlanNameAxis_CF7CDDB6D2F4423246AAD589CC702193" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanNameDomain" xlink:label="loc_us-gaap_RetirementPlanNameDomain_0264147B9AA0AA28C7BDD589CC7010DA_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanNameAxis_CF7CDDB6D2F4423246AAD589CC702193" xlink:to="loc_us-gaap_RetirementPlanNameDomain_0264147B9AA0AA28C7BDD589CC7010DA_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanNameDomain" xlink:label="loc_us-gaap_RetirementPlanNameDomain_0264147B9AA0AA28C7BDD589CC7010DA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanNameAxis_CF7CDDB6D2F4423246AAD589CC702193" xlink:to="loc_us-gaap_RetirementPlanNameDomain_0264147B9AA0AA28C7BDD589CC7010DA" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_OfficerMedicalPlanMember" xlink:label="loc_bah_OfficerMedicalPlanMember_BF5CB818D637601B5D9CD589CC716B7C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanNameDomain_0264147B9AA0AA28C7BDD589CC7010DA" xlink:to="loc_bah_OfficerMedicalPlanMember_BF5CB818D637601B5D9CD589CC716B7C" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_RetiredOfficersBonusPlanMember" xlink:label="loc_bah_RetiredOfficersBonusPlanMember_31381A2392EBFF882923D589CC712CEB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanNameDomain_0264147B9AA0AA28C7BDD589CC7010DA" xlink:to="loc_bah_RetiredOfficersBonusPlanMember_31381A2392EBFF882923D589CC712CEB" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_RetiredVicePresidentsBonusPlanMember" xlink:label="loc_bah_RetiredVicePresidentsBonusPlanMember_17C85DDB32F2F645A884D589CC7108B7" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanNameDomain_0264147B9AA0AA28C7BDD589CC7010DA" xlink:to="loc_bah_RetiredVicePresidentsBonusPlanMember_17C85DDB32F2F645A884D589CC7108B7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanTypeAxis" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_DE217A643F840D470ED7D589CC72981D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_507540C7A188D3C9B61BD589CC6FCA7E" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_DE217A643F840D470ED7D589CC72981D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_F0C52C1976D0E4C3806DD589CC72470A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_DE217A643F840D470ED7D589CC72981D" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_F0C52C1976D0E4C3806DD589CC72470A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_F0C52C1976D0E4C3806DD589CC72470A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_DE217A643F840D470ED7D589CC72981D" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_F0C52C1976D0E4C3806DD589CC72470A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_466924C485181693AA14D589CC727AFF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_F0C52C1976D0E4C3806DD589CC72470A" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_466924C485181693AA14D589CC727AFF" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DefinedBenefitPlanHealthCareCostTrendRateAssumedForNextFiscalYearPre65" xlink:label="loc_bah_DefinedBenefitPlanHealthCareCostTrendRateAssumedForNextFiscalYearPre65_E58E51176FC368EAA18DD589CC73658A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_E47FEC470FEA95E8587AD589CC730245" xlink:to="loc_bah_DefinedBenefitPlanHealthCareCostTrendRateAssumedForNextFiscalYearPre65_E58E51176FC368EAA18DD589CC73658A" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DefinedBenefitPlanUltimateHealthCareCostTrendRatePre65" xlink:label="loc_bah_DefinedBenefitPlanUltimateHealthCareCostTrendRatePre65_B3D5DC93D376B082D29ED589CC747C58" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_E47FEC470FEA95E8587AD589CC730245" xlink:to="loc_bah_DefinedBenefitPlanUltimateHealthCareCostTrendRatePre65_B3D5DC93D376B082D29ED589CC747C58" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DefinedBenefitPlanYearThatRateReachesUltimateTrendRatePre65" xlink:label="loc_bah_DefinedBenefitPlanYearThatRateReachesUltimateTrendRatePre65_7189915C52D4EC97D886D589CC74A24A" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_E47FEC470FEA95E8587AD589CC730245" xlink:to="loc_bah_DefinedBenefitPlanYearThatRateReachesUltimateTrendRatePre65_7189915C52D4EC97D886D589CC74A24A" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DefinedBenefitPlanHealthCareCostTrendRateAssumedForNextFiscalYearPost65" xlink:label="loc_bah_DefinedBenefitPlanHealthCareCostTrendRateAssumedForNextFiscalYearPost65_BB805D15781429F622BED589CC74F148" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_E47FEC470FEA95E8587AD589CC730245" xlink:to="loc_bah_DefinedBenefitPlanHealthCareCostTrendRateAssumedForNextFiscalYearPost65_BB805D15781429F622BED589CC74F148" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DefinedBenefitPlanUltimateHealthCareCostTrendRatePost65" xlink:label="loc_bah_DefinedBenefitPlanUltimateHealthCareCostTrendRatePost65_C194BA60FCA8E0E6361ED589CC745FE6" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_E47FEC470FEA95E8587AD589CC730245" xlink:to="loc_bah_DefinedBenefitPlanUltimateHealthCareCostTrendRatePost65_C194BA60FCA8E0E6361ED589CC745FE6" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DefinedBenefitPlanYearThatRateReachesUltimateTrendRatePost65" xlink:label="loc_bah_DefinedBenefitPlanYearThatRateReachesUltimateTrendRatePost65_D1E72D84DF0A373AF27CD589CC74E84E" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_E47FEC470FEA95E8587AD589CC730245" xlink:to="loc_bah_DefinedBenefitPlanYearThatRateReachesUltimateTrendRatePost65_D1E72D84DF0A373AF27CD589CC74E84E" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EmployeeBenefitPlansNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_94BF0D75942A225FA68DEA0F8DA20E3D" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_2BA24AADE30C472FF052EA0F8DA12C1F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_94BF0D75942A225FA68DEA0F8DA20E3D" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_2BA24AADE30C472FF052EA0F8DA12C1F" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanTypeAxis" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_E9385F0CA9AF79B8EC1DEA0F8DA10C45" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_2BA24AADE30C472FF052EA0F8DA12C1F" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_E9385F0CA9AF79B8EC1DEA0F8DA10C45" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_FA231269AC1B6864F81CEA0F8DA2BEF0_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_E9385F0CA9AF79B8EC1DEA0F8DA10C45" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_FA231269AC1B6864F81CEA0F8DA2BEF0_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_FA231269AC1B6864F81CEA0F8DA2BEF0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_E9385F0CA9AF79B8EC1DEA0F8DA10C45" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_FA231269AC1B6864F81CEA0F8DA2BEF0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SupplementalEmployeeRetirementPlanDefinedBenefitMember" xlink:label="loc_us-gaap_SupplementalEmployeeRetirementPlanDefinedBenefitMember_A78A8CF9C32E4199C236EA0F8DA2C0C9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_FA231269AC1B6864F81CEA0F8DA2BEF0" xlink:to="loc_us-gaap_SupplementalEmployeeRetirementPlanDefinedBenefitMember_A78A8CF9C32E4199C236EA0F8DA2C0C9" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DeferredCompensationArrangementWithIndividualAnnualCashAwardGrantedPerYearOfServiceAmount" xlink:label="loc_bah_DeferredCompensationArrangementWithIndividualAnnualCashAwardGrantedPerYearOfServiceAmount_A0C273C8DEFF7B59D32DEA0F8DA35949" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_94BF0D75942A225FA68DEA0F8DA20E3D" xlink:to="loc_bah_DeferredCompensationArrangementWithIndividualAnnualCashAwardGrantedPerYearOfServiceAmount_A0C273C8DEFF7B59D32DEA0F8DA35949" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PostemploymentBenefitsLiabilityNoncurrent" xlink:label="loc_us-gaap_PostemploymentBenefitsLiabilityNoncurrent_134B4CF7F9272D4B503AEA0F8DA3BA98" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_94BF0D75942A225FA68DEA0F8DA20E3D" xlink:to="loc_us-gaap_PostemploymentBenefitsLiabilityNoncurrent_134B4CF7F9272D4B503AEA0F8DA3BA98" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_IncreaseDecreaseInPostemploymentBenefitsLiabilityNoncurrent" xlink:label="loc_bah_IncreaseDecreaseInPostemploymentBenefitsLiabilityNoncurrent_5A96C85CDC9226F2DFF6EA0F8DA318FD" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_94BF0D75942A225FA68DEA0F8DA20E3D" xlink:to="loc_bah_IncreaseDecreaseInPostemploymentBenefitsLiabilityNoncurrent_5A96C85CDC9226F2DFF6EA0F8DA318FD" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DeferredCompensationPlansMaximumEligibleDeferralofCompensationPercentage" xlink:label="loc_bah_DeferredCompensationPlansMaximumEligibleDeferralofCompensationPercentage_22CCE521A36558E32629EA169F7BAFF9" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_94BF0D75942A225FA68DEA0F8DA20E3D" xlink:to="loc_bah_DeferredCompensationPlansMaximumEligibleDeferralofCompensationPercentage_22CCE521A36558E32629EA169F7BAFF9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredCompensationPlanAssets" xlink:label="loc_us-gaap_DeferredCompensationPlanAssets_2DC506F97E5C3960230AEA0F8DA3913E" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_94BF0D75942A225FA68DEA0F8DA20E3D" xlink:to="loc_us-gaap_DeferredCompensationPlanAssets_2DC506F97E5C3960230AEA0F8DA3913E" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EmployeeBenefitPlansRetiredOfficersBonusPlanAndRetiredVpBonusPlanDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_652E2665D7BC9F720F04FB2438532E04" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_61AC2159A19B6A977048FB24384F0862" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_652E2665D7BC9F720F04FB2438532E04" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_61AC2159A19B6A977048FB24384F0862" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanNameAxis" xlink:label="loc_us-gaap_RetirementPlanNameAxis_43B5BE79B3215120CB5EFB24384FA8BD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_61AC2159A19B6A977048FB24384F0862" xlink:to="loc_us-gaap_RetirementPlanNameAxis_43B5BE79B3215120CB5EFB24384FA8BD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanNameDomain" xlink:label="loc_us-gaap_RetirementPlanNameDomain_B0D2609FBBCDE6EB3D30FB24384F93C4_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanNameAxis_43B5BE79B3215120CB5EFB24384FA8BD" xlink:to="loc_us-gaap_RetirementPlanNameDomain_B0D2609FBBCDE6EB3D30FB24384F93C4_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanNameDomain" xlink:label="loc_us-gaap_RetirementPlanNameDomain_B0D2609FBBCDE6EB3D30FB24384F93C4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanNameAxis_43B5BE79B3215120CB5EFB24384FA8BD" xlink:to="loc_us-gaap_RetirementPlanNameDomain_B0D2609FBBCDE6EB3D30FB24384F93C4" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_RetiredOfficersBonusPlanMember" xlink:label="loc_bah_RetiredOfficersBonusPlanMember_61BD5D72A2EAADC8E56FFB24384F8DB7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanNameDomain_B0D2609FBBCDE6EB3D30FB24384F93C4" xlink:to="loc_bah_RetiredOfficersBonusPlanMember_61BD5D72A2EAADC8E56FFB24384F8DB7" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_RetiredVicePresidentsBonusPlanMember" xlink:label="loc_bah_RetiredVicePresidentsBonusPlanMember_B73DD16818F884F37ABEFB24384F0B04" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanNameDomain_B0D2609FBBCDE6EB3D30FB24384F93C4" xlink:to="loc_bah_RetiredVicePresidentsBonusPlanMember_B73DD16818F884F37ABEFB24384F0B04" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_OfficerMedicalPlanMember" xlink:label="loc_bah_OfficerMedicalPlanMember_6C3BEFA889DB58E5FED4FB2FBE6B6459" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanNameDomain_B0D2609FBBCDE6EB3D30FB24384F93C4" xlink:to="loc_bah_OfficerMedicalPlanMember_6C3BEFA889DB58E5FED4FB2FBE6B6459" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanTypeAxis" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_4649369896745F84A4EDFB24384F7816" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_61AC2159A19B6A977048FB24384F0862" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_4649369896745F84A4EDFB24384F7816" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_6CC82E93A1D77A9C0A56FB24384F11F3_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_4649369896745F84A4EDFB24384F7816" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_6CC82E93A1D77A9C0A56FB24384F11F3_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_6CC82E93A1D77A9C0A56FB24384F11F3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_4649369896745F84A4EDFB24384F7816" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_6CC82E93A1D77A9C0A56FB24384F11F3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_6B8D66F0F9FA04FE35D3FB24384F5465" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_6CC82E93A1D77A9C0A56FB24384F11F3" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_6B8D66F0F9FA04FE35D3FB24384F5465" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TitleOfIndividualAxis" xlink:label="loc_us-gaap_TitleOfIndividualAxis_1C4A94AFEFFB29C8378DFB24384F2DDD" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_61AC2159A19B6A977048FB24384F0862" xlink:to="loc_us-gaap_TitleOfIndividualAxis_1C4A94AFEFFB29C8378DFB24384F2DDD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_45849BA8486D51963257FB24384F06BF_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TitleOfIndividualAxis_1C4A94AFEFFB29C8378DFB24384F2DDD" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_45849BA8486D51963257FB24384F06BF_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_45849BA8486D51963257FB24384F06BF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TitleOfIndividualAxis_1C4A94AFEFFB29C8378DFB24384F2DDD" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_45849BA8486D51963257FB24384F06BF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OfficerMember" xlink:label="loc_us-gaap_OfficerMember_4C5DC72537099D9D7AF1FB243853240B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_45849BA8486D51963257FB24384F06BF" xlink:to="loc_us-gaap_OfficerMember_4C5DC72537099D9D7AF1FB243853240B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_F6F8E794A05BA01B6F64FB243853B77E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_652E2665D7BC9F720F04FB2438532E04" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_F6F8E794A05BA01B6F64FB243853B77E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid_08DABF54E49BE7EFE998FB2438536AAE" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_652E2665D7BC9F720F04FB2438532E04" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid_08DABF54E49BE7EFE998FB2438536AAE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanFundedStatusOfPlan" xlink:label="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_EA631F98B6E92A7AFF90FB243854D941" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_652E2665D7BC9F720F04FB2438532E04" xlink:to="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_EA631F98B6E92A7AFF90FB243854D941" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanBenefitObligation" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligation_5A962921C5D10841B95CFB243854CB2D" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_652E2665D7BC9F720F04FB2438532E04" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligation_5A962921C5D10841B95CFB243854CB2D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" xlink:label="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_6263AF607FBA1E39301AFB3031D64C21" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_652E2665D7BC9F720F04FB2438532E04" xlink:to="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_6263AF607FBA1E39301AFB3031D64C21" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EmployeeBenefitPlansTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EmployeeBenefitPlansWeightedAverageDiscountRateDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_59C0EFC6952A504E97D9160FB351BE46" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_79FEDAAF77775C559A9F5A9697BCB1BC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_59C0EFC6952A504E97D9160FB351BE46" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_79FEDAAF77775C559A9F5A9697BCB1BC" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanNameAxis" xlink:label="loc_us-gaap_RetirementPlanNameAxis_65451A09822E52E6A0400A0CC53451AD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_79FEDAAF77775C559A9F5A9697BCB1BC" xlink:to="loc_us-gaap_RetirementPlanNameAxis_65451A09822E52E6A0400A0CC53451AD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanNameDomain" xlink:label="loc_us-gaap_RetirementPlanNameDomain_6E57333E99AF445CF450E666C328605A_3A03FFEE806B57A6BB951B08A10A2E36" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanNameAxis_65451A09822E52E6A0400A0CC53451AD" xlink:to="loc_us-gaap_RetirementPlanNameDomain_6E57333E99AF445CF450E666C328605A_3A03FFEE806B57A6BB951B08A10A2E36" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanNameDomain" xlink:label="loc_us-gaap_RetirementPlanNameDomain_2A415C242F685F63A55FE7BAA5F5B097" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanNameAxis_65451A09822E52E6A0400A0CC53451AD" xlink:to="loc_us-gaap_RetirementPlanNameDomain_2A415C242F685F63A55FE7BAA5F5B097" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_OfficerMedicalPlanMember" xlink:label="loc_bah_OfficerMedicalPlanMember_2E9780EEA91C5E43A64A1BB29B1B010B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanNameDomain_2A415C242F685F63A55FE7BAA5F5B097" xlink:to="loc_bah_OfficerMedicalPlanMember_2E9780EEA91C5E43A64A1BB29B1B010B" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_RetiredOfficersBonusPlanMember" xlink:label="loc_bah_RetiredOfficersBonusPlanMember_3724AC475BE15B1DA7173461E7509702" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanNameDomain_2A415C242F685F63A55FE7BAA5F5B097" xlink:to="loc_bah_RetiredOfficersBonusPlanMember_3724AC475BE15B1DA7173461E7509702" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_RetiredVicePresidentsBonusPlanMember" xlink:label="loc_bah_RetiredVicePresidentsBonusPlanMember_ADFFF106D08555BFBEE472953E3A3A1F" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanNameDomain_2A415C242F685F63A55FE7BAA5F5B097" xlink:to="loc_bah_RetiredVicePresidentsBonusPlanMember_ADFFF106D08555BFBEE472953E3A3A1F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanTypeAxis" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_F56A1ED708F05542A2D0671BDE97A432" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_79FEDAAF77775C559A9F5A9697BCB1BC" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_F56A1ED708F05542A2D0671BDE97A432" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_EC611955E9EBBD183EC8E666C329CB66_3A03FFEE806B57A6BB951B08A10A2E36" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_F56A1ED708F05542A2D0671BDE97A432" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_EC611955E9EBBD183EC8E666C329CB66_3A03FFEE806B57A6BB951B08A10A2E36" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_E37A7D22B44F52F98F54F212F2330E4C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_F56A1ED708F05542A2D0671BDE97A432" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_E37A7D22B44F52F98F54F212F2330E4C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_3C67673EBC9D5D52A0E62E169AEFD11D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_E37A7D22B44F52F98F54F212F2330E4C" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_3C67673EBC9D5D52A0E62E169AEFD11D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate_F171FBE7F1FA5D6380A5A72890C09997" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_59C0EFC6952A504E97D9160FB351BE46" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate_F171FBE7F1FA5D6380A5A72890C09997" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/FairValueMeasurements" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/FairValueMeasurementsScheduleOfRecurringFairValueMeasurementsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_3B6D2F96D0809C922218EB493E11011E" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_66692EA2A80644988FFEEB493E07B273" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_3B6D2F96D0809C922218EB493E11011E" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_66692EA2A80644988FFEEB493E07B273" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_AE479DC6CA8EC4038656EB493E071DE6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_66692EA2A80644988FFEEB493E07B273" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_AE479DC6CA8EC4038656EB493E071DE6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_F0EBD7F7AA7965B2092AEB493E0842A6_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_AE479DC6CA8EC4038656EB493E071DE6" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_F0EBD7F7AA7965B2092AEB493E0842A6_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_F0EBD7F7AA7965B2092AEB493E0842A6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_AE479DC6CA8EC4038656EB493E071DE6" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_F0EBD7F7AA7965B2092AEB493E0842A6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherNoncurrentLiabilitiesMember" xlink:label="loc_us-gaap_OtherNoncurrentLiabilitiesMember_C7BB8749050680C756CBEB493E085C7D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_F0EBD7F7AA7965B2092AEB493E0842A6" xlink:to="loc_us-gaap_OtherNoncurrentLiabilitiesMember_C7BB8749050680C756CBEB493E085C7D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_E0E507CA0742CEE37148EB493E09DD28" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_66692EA2A80644988FFEEB493E07B273" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_E0E507CA0742CEE37148EB493E09DD28" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_EB46C84E72A1A5E4271DEB493E09B3A6_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_E0E507CA0742CEE37148EB493E09DD28" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_EB46C84E72A1A5E4271DEB493E09B3A6_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_EB46C84E72A1A5E4271DEB493E09B3A6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_E0E507CA0742CEE37148EB493E09DD28" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_EB46C84E72A1A5E4271DEB493E09B3A6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_73B4AEBCD1D1F70ADF7DEB493E0AD9C9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_EB46C84E72A1A5E4271DEB493E09B3A6" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_73B4AEBCD1D1F70ADF7DEB493E0AD9C9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_68E870C1F0FFD81D3F2FEB493E0B5FBD" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_66692EA2A80644988FFEEB493E07B273" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_68E870C1F0FFD81D3F2FEB493E0B5FBD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2D4EA950E1777DB7DFDCEB493E0BFD6A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_68E870C1F0FFD81D3F2FEB493E0B5FBD" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2D4EA950E1777DB7DFDCEB493E0BFD6A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2D4EA950E1777DB7DFDCEB493E0BFD6A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_68E870C1F0FFD81D3F2FEB493E0B5FBD" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2D4EA950E1777DB7DFDCEB493E0BFD6A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_9FFC6CE8D8A4B362B4B8EB493E108CFF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2D4EA950E1777DB7DFDCEB493E0BFD6A" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_9FFC6CE8D8A4B362B4B8EB493E108CFF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_601FB00897BDA82BAA30EB493E101783" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2D4EA950E1777DB7DFDCEB493E0BFD6A" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_601FB00897BDA82BAA30EB493E101783" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_EDB55833B1EB06F07695EB493E111C01" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2D4EA950E1777DB7DFDCEB493E0BFD6A" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_EDB55833B1EB06F07695EB493E111C01" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AssetsFairValueDisclosureAbstract" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_EE33CC562F3F2B7BB968EB493E11FB29" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_3B6D2F96D0809C922218EB493E11011E" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_EE33CC562F3F2B7BB968EB493E11FB29" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeAssetsCurrent" xlink:label="loc_us-gaap_DerivativeAssetsCurrent_3485D71ECD9B010AEAEDEB493E11912E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_EE33CC562F3F2B7BB968EB493E11FB29" xlink:to="loc_us-gaap_DerivativeAssetsCurrent_3485D71ECD9B010AEAEDEB493E11912E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeAssetsNoncurrent" xlink:label="loc_us-gaap_DerivativeAssetsNoncurrent_2D4AACAE1CAF2A662C4DEB493E127335" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_EE33CC562F3F2B7BB968EB493E11FB29" xlink:to="loc_us-gaap_DerivativeAssetsNoncurrent_2D4AACAE1CAF2A662C4DEB493E127335" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredCompensationPlanAssets" xlink:label="loc_us-gaap_DeferredCompensationPlanAssets_23D79FFF80786E89877DEB493E123B57" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_EE33CC562F3F2B7BB968EB493E11FB29" xlink:to="loc_us-gaap_DeferredCompensationPlanAssets_23D79FFF80786E89877DEB493E123B57" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherAssetsFairValueDisclosure" xlink:label="loc_us-gaap_OtherAssetsFairValueDisclosure_44CDABFE7CEC0E5D06B6EB493E12857A" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_EE33CC562F3F2B7BB968EB493E11FB29" xlink:to="loc_us-gaap_OtherAssetsFairValueDisclosure_44CDABFE7CEC0E5D06B6EB493E12857A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LiabilitiesFairValueDisclosureAbstract" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_171D2DCBDF4B5363CDF0EB493E12AB3B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_3B6D2F96D0809C922218EB493E11011E" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_171D2DCBDF4B5363CDF0EB493E12AB3B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent_0F47CD922FCCA46B9653EB493E128827" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_171D2DCBDF4B5363CDF0EB493E12AB3B" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent_0F47CD922FCCA46B9653EB493E128827" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeLiabilitiesCurrent" xlink:label="loc_us-gaap_DerivativeLiabilitiesCurrent_E8E14348A638688E2C32EB493E13C1B3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_171D2DCBDF4B5363CDF0EB493E12AB3B" xlink:to="loc_us-gaap_DerivativeLiabilitiesCurrent_E8E14348A638688E2C32EB493E13C1B3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeLiabilitiesNoncurrent" xlink:label="loc_us-gaap_DerivativeLiabilitiesNoncurrent_23A2DDCA8E9C490394ACEB493E1315A9" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_171D2DCBDF4B5363CDF0EB493E12AB3B" xlink:to="loc_us-gaap_DerivativeLiabilitiesNoncurrent_23A2DDCA8E9C490394ACEB493E1315A9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent" xlink:label="loc_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_6024155D945D01D6484AEB493E132E79" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_171D2DCBDF4B5363CDF0EB493E12AB3B" xlink:to="loc_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_6024155D945D01D6484AEB493E132E79" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinancialLiabilitiesFairValueDisclosure" xlink:label="loc_us-gaap_FinancialLiabilitiesFairValueDisclosure_4061005467E75BC9125DEB493E1367B5" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_171D2DCBDF4B5363CDF0EB493E12AB3B" xlink:to="loc_us-gaap_FinancialLiabilitiesFairValueDisclosure_4061005467E75BC9125DEB493E1367B5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_2BFBBD1224CA84AA8A64EB493E13F326" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_3B6D2F96D0809C922218EB493E11011E" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_2BFBBD1224CA84AA8A64EB493E13F326" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/FairValueMeasurementsTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/GoodwillAndIntangibleAssets" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/GoodwillAndIntangibleAssetsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_D0097F37F7BE050C117A98E53198076B" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_FED389DE584B5FAD4A7E98E53194262D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_D0097F37F7BE050C117A98E53198076B" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_FED389DE584B5FAD4A7E98E53194262D" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_0A66D7658C37533BA38198E531953140" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_FED389DE584B5FAD4A7E98E53194262D" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_0A66D7658C37533BA38198E531953140" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_0A5E5B4ADA158F2A416698E53195050E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_0A66D7658C37533BA38198E531953140" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_0A5E5B4ADA158F2A416698E53195050E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_0A5E5B4ADA158F2A416698E53195050E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_0A66D7658C37533BA38198E531953140" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_0A5E5B4ADA158F2A416698E53195050E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OrderOrProductionBacklogMember" xlink:label="loc_us-gaap_OrderOrProductionBacklogMember_23ECC800155F40D6FD9698E53196C9F1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_0A5E5B4ADA158F2A416698E53195050E" xlink:to="loc_us-gaap_OrderOrProductionBacklogMember_23ECC800155F40D6FD9698E53196C9F1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_BE637E259D5B95E6431398E53196B360" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_FED389DE584B5FAD4A7E98E53194262D" xlink:to="loc_srt_RangeAxis_BE637E259D5B95E6431398E53196B360" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_610A4C88E220FE3570F598E53196B986_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_BE637E259D5B95E6431398E53196B360" xlink:to="loc_srt_RangeMember_610A4C88E220FE3570F598E53196B986_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_610A4C88E220FE3570F598E53196B986" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_BE637E259D5B95E6431398E53196B360" xlink:to="loc_srt_RangeMember_610A4C88E220FE3570F598E53196B986" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_2DDE650D4ADABB1E438B98E531973DEE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_610A4C88E220FE3570F598E53196B986" xlink:to="loc_srt_MinimumMember_2DDE650D4ADABB1E438B98E531973DEE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_1BAF64BA44E18D22B45598E531985D3A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_610A4C88E220FE3570F598E53196B986" xlink:to="loc_srt_MaximumMember_1BAF64BA44E18D22B45598E531985D3A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_WeightedAverageMember" xlink:label="loc_srt_WeightedAverageMember_30B923A113DE9BFE3E1E98E531989AF0" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_610A4C88E220FE3570F598E53196B986" xlink:to="loc_srt_WeightedAverageMember_30B923A113DE9BFE3E1E98E531989AF0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_AB4B931D832B0AC3C83298E53198104A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_D0097F37F7BE050C117A98E53198076B" xlink:to="loc_us-gaap_Goodwill_AB4B931D832B0AC3C83298E53198104A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_3ECD6A6BC3338492E76798E5319891CA" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_D0097F37F7BE050C117A98E53198076B" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_3ECD6A6BC3338492E76798E5319891CA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ImpairmentOfIntangibleAssetsFinitelived" xlink:label="loc_us-gaap_ImpairmentOfIntangibleAssetsFinitelived_DCEA59087015C397E7BF98E531996159" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_D0097F37F7BE050C117A98E53198076B" xlink:to="loc_us-gaap_ImpairmentOfIntangibleAssetsFinitelived_DCEA59087015C397E7BF98E531996159" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_869738B96FE732D2ED4498E53199A965" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_D0097F37F7BE050C117A98E53198076B" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_869738B96FE732D2ED4498E53199A965" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/GoodwillAndIntangibleAssetsScheduleOfExpectedAmortizationExpenseDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/GoodwillAndIntangibleAssetsScheduleOfFiniteLivedIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_A3CBC4B89FED0BB030B6EA0F8EE0787C" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_5F0C317E41392D5B51F9EA0F8EDD8336" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_A3CBC4B89FED0BB030B6EA0F8EE0787C" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_5F0C317E41392D5B51F9EA0F8EDD8336" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_A8DBC4628FF7BE7EF1AFEA0F8EDD10A0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_5F0C317E41392D5B51F9EA0F8EDD8336" xlink:to="loc_srt_RangeAxis_A8DBC4628FF7BE7EF1AFEA0F8EDD10A0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_20682F8C3C2BD337B87EEA0F8EDE228D_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_A8DBC4628FF7BE7EF1AFEA0F8EDD10A0" xlink:to="loc_srt_RangeMember_20682F8C3C2BD337B87EEA0F8EDE228D_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_20682F8C3C2BD337B87EEA0F8EDE228D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_A8DBC4628FF7BE7EF1AFEA0F8EDD10A0" xlink:to="loc_srt_RangeMember_20682F8C3C2BD337B87EEA0F8EDE228D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_WeightedAverageMember" xlink:label="loc_srt_WeightedAverageMember_AA2B1896B19A825BE0EAEA0F8EDE46D4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_20682F8C3C2BD337B87EEA0F8EDE228D" xlink:to="loc_srt_WeightedAverageMember_AA2B1896B19A825BE0EAEA0F8EDE46D4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_E4F81064D0774657DEE7EA0F8EDE3469" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_5F0C317E41392D5B51F9EA0F8EDD8336" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_E4F81064D0774657DEE7EA0F8EDE3469" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_6D80E9C0D10D06416367EA0F8EDFBCCC_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_E4F81064D0774657DEE7EA0F8EDE3469" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_6D80E9C0D10D06416367EA0F8EDFBCCC_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_6D80E9C0D10D06416367EA0F8EDFBCCC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_E4F81064D0774657DEE7EA0F8EDE3469" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_6D80E9C0D10D06416367EA0F8EDFBCCC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OrderOrProductionBacklogMember" xlink:label="loc_us-gaap_OrderOrProductionBacklogMember_281CC17AD31EC1A55789EA0F8EDF9C82" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_6D80E9C0D10D06416367EA0F8EDFBCCC" xlink:to="loc_us-gaap_OrderOrProductionBacklogMember_281CC17AD31EC1A55789EA0F8EDF9C82" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ComputerSoftwareIntangibleAssetMember" xlink:label="loc_us-gaap_ComputerSoftwareIntangibleAssetMember_A9F8AFAABA0C6F320EB9EA0F8EDFDA85" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_6D80E9C0D10D06416367EA0F8EDFBCCC" xlink:to="loc_us-gaap_ComputerSoftwareIntangibleAssetMember_A9F8AFAABA0C6F320EB9EA0F8EDFDA85" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_AC26F147A62D3992E505EA0F8EDF6F60" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_5F0C317E41392D5B51F9EA0F8EDD8336" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_AC26F147A62D3992E505EA0F8EDF6F60" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_B597F2097AC339A35E6EEA0F8EE032C8_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_AC26F147A62D3992E505EA0F8EDF6F60" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_B597F2097AC339A35E6EEA0F8EE032C8_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_B597F2097AC339A35E6EEA0F8EE032C8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_AC26F147A62D3992E505EA0F8EDF6F60" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_B597F2097AC339A35E6EEA0F8EE032C8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TradeNamesMember" xlink:label="loc_us-gaap_TradeNamesMember_433194758EF0959FFA62EA0F8EE0F6CE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_B597F2097AC339A35E6EEA0F8EE032C8" xlink:to="loc_us-gaap_TradeNamesMember_433194758EF0959FFA62EA0F8EE0F6CE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1_710A06192B932222CC51EA0F8EE0404D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_A3CBC4B89FED0BB030B6EA0F8EE0787C" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1_710A06192B932222CC51EA0F8EE0404D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNetAbstract" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_FBE480B3D1B63DB58D8BEA0F8EE15CEC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_A3CBC4B89FED0BB030B6EA0F8EE0787C" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_FBE480B3D1B63DB58D8BEA0F8EE15CEC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_00CD0E179FA89A2E2F8DEA0F8EE1A070" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_FBE480B3D1B63DB58D8BEA0F8EE15CEC" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_00CD0E179FA89A2E2F8DEA0F8EE1A070" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_74DA047DC4EB30D1232CEA0F8EE15E51" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_FBE480B3D1B63DB58D8BEA0F8EE15CEC" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_74DA047DC4EB30D1232CEA0F8EE15E51" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_E2E6E791342DAD6FE684EA0F8EE1C3AA" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_FBE480B3D1B63DB58D8BEA0F8EE15CEC" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_E2E6E791342DAD6FE684EA0F8EE1C3AA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwillAbstract" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwillAbstract_69CA1003A842425727C2EA0F8EE1F36E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_A3CBC4B89FED0BB030B6EA0F8EE0787C" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwillAbstract_69CA1003A842425727C2EA0F8EE1F36E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_C5A36CB0B2D63B70C90FEA0F8EE2E582" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwillAbstract_69CA1003A842425727C2EA0F8EE1F36E" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_C5A36CB0B2D63B70C90FEA0F8EE2E582" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IntangibleAssetsGrossExcludingGoodwill" xlink:label="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_2D3AF5322E39D5FEE9EFEA0F8EE2C2FE" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_A3CBC4B89FED0BB030B6EA0F8EE0787C" xlink:to="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_2D3AF5322E39D5FEE9EFEA0F8EE2C2FE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_BAF7E7D4A96E5E7C9BBAEA0F8EE23155" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_A3CBC4B89FED0BB030B6EA0F8EE0787C" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_BAF7E7D4A96E5E7C9BBAEA0F8EE23155" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/GoodwillAndIntangibleAssetsTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/IncomeTaxes" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/IncomeTaxesComponentsOfIncomeTaxesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/IncomeTaxesComponentsOfNetDeferredIncomeTaxesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/IncomeTaxesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLossCarryforwardsLineItems" xlink:label="loc_us-gaap_OperatingLossCarryforwardsLineItems_0A868B1A9EC544FAD922EA78BC1DB7D9" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLossCarryforwardsTable" xlink:label="loc_us-gaap_OperatingLossCarryforwardsTable_B1C0384BEB3071378592EA78BC109C54" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_0A868B1A9EC544FAD922EA78BC1DB7D9" xlink:to="loc_us-gaap_OperatingLossCarryforwardsTable_B1C0384BEB3071378592EA78BC109C54" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TaxPeriodAxis" xlink:label="loc_us-gaap_TaxPeriodAxis_562064B4D5B6C023F7C0EA78BC121CCF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_B1C0384BEB3071378592EA78BC109C54" xlink:to="loc_us-gaap_TaxPeriodAxis_562064B4D5B6C023F7C0EA78BC121CCF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TaxPeriodDomain" xlink:label="loc_us-gaap_TaxPeriodDomain_B5F5B2433922EB1D82AEEA78BC12548D_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TaxPeriodAxis_562064B4D5B6C023F7C0EA78BC121CCF" xlink:to="loc_us-gaap_TaxPeriodDomain_B5F5B2433922EB1D82AEEA78BC12548D_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TaxPeriodDomain" xlink:label="loc_us-gaap_TaxPeriodDomain_B5F5B2433922EB1D82AEEA78BC12548D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TaxPeriodAxis_562064B4D5B6C023F7C0EA78BC121CCF" xlink:to="loc_us-gaap_TaxPeriodDomain_B5F5B2433922EB1D82AEEA78BC12548D" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_TaxYears20132015Member" xlink:label="loc_bah_TaxYears20132015Member_CF38101381B46D597256EA78BC132FA1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxPeriodDomain_B5F5B2433922EB1D82AEEA78BC12548D" xlink:to="loc_bah_TaxYears20132015Member_CF38101381B46D597256EA78BC132FA1" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_TaxYears20162019Member" xlink:label="loc_bah_TaxYears20162019Member_4C5099029589F38FDD63EA78BC19DD08" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxPeriodDomain_B5F5B2433922EB1D82AEEA78BC12548D" xlink:to="loc_bah_TaxYears20162019Member_4C5099029589F38FDD63EA78BC19DD08" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_DD43E92BE1AA80919D48EA78BC1AA43C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_B1C0384BEB3071378592EA78BC109C54" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_DD43E92BE1AA80919D48EA78BC1AA43C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_849F338ACA7AB26B3A2FEA78BC1BAB9D_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_DD43E92BE1AA80919D48EA78BC1AA43C" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_849F338ACA7AB26B3A2FEA78BC1BAB9D_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_849F338ACA7AB26B3A2FEA78BC1BAB9D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_DD43E92BE1AA80919D48EA78BC1AA43C" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_849F338ACA7AB26B3A2FEA78BC1BAB9D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DomesticCountryMember" xlink:label="loc_us-gaap_DomesticCountryMember_5023856BE8ED8492358DEA78BC1CD7EC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_849F338ACA7AB26B3A2FEA78BC1BAB9D" xlink:to="loc_us-gaap_DomesticCountryMember_5023856BE8ED8492358DEA78BC1CD7EC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StateAndLocalJurisdictionMember" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_6D18C76470B0DFFB335FEA78BC1CCF67" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_849F338ACA7AB26B3A2FEA78BC1BAB9D" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_6D18C76470B0DFFB335FEA78BC1CCF67" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ForeignCountryMember" xlink:label="loc_us-gaap_ForeignCountryMember_A398678F936BAD1FE110EA78BC1C4C5C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_849F338ACA7AB26B3A2FEA78BC1BAB9D" xlink:to="loc_us-gaap_ForeignCountryMember_A398678F936BAD1FE110EA78BC1C4C5C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_CC81F0CB98D80A9CE019EA7A359F0AAF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_0A868B1A9EC544FAD922EA78BC1DB7D9" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_CC81F0CB98D80A9CE019EA7A359F0AAF" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DeferredTaxAssetsProjectedEffectiveRateAtWhichPositionWillReverse" xlink:label="loc_bah_DeferredTaxAssetsProjectedEffectiveRateAtWhichPositionWillReverse_CCD112FF0D91B530F5D6EA78BC1DAE33" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_0A868B1A9EC544FAD922EA78BC1DB7D9" xlink:to="loc_bah_DeferredTaxAssetsProjectedEffectiveRateAtWhichPositionWillReverse_CCD112FF0D91B530F5D6EA78BC1DAE33" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DeferredTaxLiabilitiesProjectedEffectiveRateAtWhichPositionWillReverse" xlink:label="loc_bah_DeferredTaxLiabilitiesProjectedEffectiveRateAtWhichPositionWillReverse_A6D14F0D96EB360530CFEA78BC1E1512" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_0A868B1A9EC544FAD922EA78BC1DB7D9" xlink:to="loc_bah_DeferredTaxLiabilitiesProjectedEffectiveRateAtWhichPositionWillReverse_A6D14F0D96EB360530CFEA78BC1E1512" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_TaxCutsAndJobsActOf2017IncompleteAccountingChangeInTaxRateProvisionalIncomeTaxExpenseBenefit" xlink:label="loc_bah_TaxCutsAndJobsActOf2017IncompleteAccountingChangeInTaxRateProvisionalIncomeTaxExpenseBenefit_858747607E8B5FE0D186EA78BC1E8044" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_0A868B1A9EC544FAD922EA78BC1DB7D9" xlink:to="loc_bah_TaxCutsAndJobsActOf2017IncompleteAccountingChangeInTaxRateProvisionalIncomeTaxExpenseBenefit_858747607E8B5FE0D186EA78BC1E8044" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLossCarryforwards" xlink:label="loc_us-gaap_OperatingLossCarryforwards_DCC6F5BDE3696220CD64EA78BC1F55DE" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_0A868B1A9EC544FAD922EA78BC1DB7D9" xlink:to="loc_us-gaap_OperatingLossCarryforwards_DCC6F5BDE3696220CD64EA78BC1F55DE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLossCarryforwardsValuationAllowance" xlink:label="loc_us-gaap_OperatingLossCarryforwardsValuationAllowance_43019428B9D51E750124EA78BC202ACE" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_0A868B1A9EC544FAD922EA78BC1DB7D9" xlink:to="loc_us-gaap_OperatingLossCarryforwardsValuationAllowance_43019428B9D51E750124EA78BC202ACE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LiabilityForUncertainTaxPositionsNoncurrent" xlink:label="loc_us-gaap_LiabilityForUncertainTaxPositionsNoncurrent_A5AC67B14320A9F01A17EA78BC200A3E" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_0A868B1A9EC544FAD922EA78BC1DB7D9" xlink:to="loc_us-gaap_LiabilityForUncertainTaxPositionsNoncurrent_A5AC67B14320A9F01A17EA78BC200A3E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate_4BBCDCD818F1766CB15CEA78BC210698" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_0A868B1A9EC544FAD922EA78BC1DB7D9" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate_4BBCDCD818F1766CB15CEA78BC210698" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense_0F45BBAD5655D3972B77EA78BC217885" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_0A868B1A9EC544FAD922EA78BC1DB7D9" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense_0F45BBAD5655D3972B77EA78BC217885" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_CA6A024FF75B111EB174EA78BC22E942" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_0A868B1A9EC544FAD922EA78BC1DB7D9" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_CA6A024FF75B111EB174EA78BC22E942" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxExaminationLiabilityRefundAdjustmentFromSettlementWithTaxingAuthority" xlink:label="loc_us-gaap_IncomeTaxExaminationLiabilityRefundAdjustmentFromSettlementWithTaxingAuthority_4322A40E8F01C9218F67EA78BC22FCCA" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_0A868B1A9EC544FAD922EA78BC1DB7D9" xlink:to="loc_us-gaap_IncomeTaxExaminationLiabilityRefundAdjustmentFromSettlementWithTaxingAuthority_4322A40E8F01C9218F67EA78BC22FCCA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxExaminationEstimateOfPossibleLoss" xlink:label="loc_us-gaap_IncomeTaxExaminationEstimateOfPossibleLoss_49595436D4C871B74F09EA78BC226497" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_0A868B1A9EC544FAD922EA78BC1DB7D9" xlink:to="loc_us-gaap_IncomeTaxExaminationEstimateOfPossibleLoss_49595436D4C871B74F09EA78BC226497" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward" xlink:label="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_CF9A312CEFDC2EE18214EA78BC22B23B" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_0A868B1A9EC544FAD922EA78BC1DB7D9" xlink:to="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_CF9A312CEFDC2EE18214EA78BC22B23B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_UnrecognizedTaxBenefits" xlink:label="loc_us-gaap_UnrecognizedTaxBenefits_3A34D2FAC75B6513EF9DEA78BC237449" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_CF9A312CEFDC2EE18214EA78BC22B23B" xlink:to="loc_us-gaap_UnrecognizedTaxBenefits_3A34D2FAC75B6513EF9DEA78BC237449" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions_B06FFE96C5E7E2B2D4FFEA78BC273F6A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_CF9A312CEFDC2EE18214EA78BC22B23B" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions_B06FFE96C5E7E2B2D4FFEA78BC273F6A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions_8C2A6DFCB998545BCFA3EA78BC28E9D3" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_CF9A312CEFDC2EE18214EA78BC22B23B" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions_8C2A6DFCB998545BCFA3EA78BC28E9D3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities_83F58ED6D20770E7F4ABEA78BC28C716" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_CF9A312CEFDC2EE18214EA78BC22B23B" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities_83F58ED6D20770E7F4ABEA78BC28C716" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations_35214C9EF79FD9E57FE7EA78BC29C2B6" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_CF9A312CEFDC2EE18214EA78BC22B23B" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations_35214C9EF79FD9E57FE7EA78BC29C2B6" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/IncomeTaxesReconciliationOfIncomeTaxDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/IncomeTaxesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/OtherLongTermLiabilities" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/OtherLongTermLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_084296501F742FB339F8C5DEDBCE542E" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_F994FB72EA6F4FBBEAAEC5DEDBCD6125" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_084296501F742FB339F8C5DEDBCE542E" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_F994FB72EA6F4FBBEAAEC5DEDBCD6125" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3A55809F19A79E71F43EC676B418787A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_F994FB72EA6F4FBBEAAEC5DEDBCD6125" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3A55809F19A79E71F43EC676B418787A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_4FDAB795B674514F8719C676B4199C7C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3A55809F19A79E71F43EC676B418787A" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_4FDAB795B674514F8719C676B4199C7C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_4FDAB795B674514F8719C676B4199C7C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3A55809F19A79E71F43EC676B418787A" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_4FDAB795B674514F8719C676B4199C7C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_CF544DECA2C5F3A8C244C676B44D3FEA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_4FDAB795B674514F8719C676B4199C7C" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_CF544DECA2C5F3A8C244C676B44D3FEA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_7A1DEADF30C68BBA7B0CC676B40018FA" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_F994FB72EA6F4FBBEAAEC5DEDBCD6125" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_7A1DEADF30C68BBA7B0CC676B40018FA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6B875EA4664B38954914C676B4011FBC_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_7A1DEADF30C68BBA7B0CC676B40018FA" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6B875EA4664B38954914C676B4011FBC_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6B875EA4664B38954914C676B4011FBC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_7A1DEADF30C68BBA7B0CC676B40018FA" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6B875EA4664B38954914C676B4011FBC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_6392B2DB89E44EA065DEC676B43F745D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6B875EA4664B38954914C676B4011FBC" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_6392B2DB89E44EA065DEC676B43F745D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_333DB8496FE6D3034541C676B3EAEC7C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_F994FB72EA6F4FBBEAAEC5DEDBCD6125" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_333DB8496FE6D3034541C676B3EAEC7C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_EAC945DA4B38094BAC82C676B3EB7FFE_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_333DB8496FE6D3034541C676B3EAEC7C" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_EAC945DA4B38094BAC82C676B3EB7FFE_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_EAC945DA4B38094BAC82C676B3EB7FFE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_333DB8496FE6D3034541C676B3EAEC7C" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_EAC945DA4B38094BAC82C676B3EB7FFE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherNoncurrentLiabilitiesMember" xlink:label="loc_us-gaap_OtherNoncurrentLiabilitiesMember_C6BB47ED7C0A242C5FDBC676B4314CC6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_EAC945DA4B38094BAC82C676B3EB7FFE" xlink:to="loc_us-gaap_OtherNoncurrentLiabilitiesMember_C6BB47ED7C0A242C5FDBC676B4314CC6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PostemploymentBenefitsLiabilityNoncurrent" xlink:label="loc_us-gaap_PostemploymentBenefitsLiabilityNoncurrent_00E435C1CA3197F75E06C5DEDBCECF4E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_084296501F742FB339F8C5DEDBCE542E" xlink:to="loc_us-gaap_PostemploymentBenefitsLiabilityNoncurrent_00E435C1CA3197F75E06C5DEDBCECF4E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent_DBCE5C76EF2CEEA59CA6C676B3DEB1D7" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_084296501F742FB339F8C5DEDBCE542E" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent_DBCE5C76EF2CEEA59CA6C676B3DEB1D7" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/OtherLongTermLiabilitiesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/PropertyAndEquipmentNet" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/PropertyAndEquipmentNetDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_2A0F05F7C1B2E49AA5FDEA0F8EBD7788" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_9B5E859E0C93C033879CEA0F8EBB6B83" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_2A0F05F7C1B2E49AA5FDEA0F8EBD7788" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_9B5E859E0C93C033879CEA0F8EBB6B83" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_893091CDC77BCEEC8F50EA0F8EBB6409" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_9B5E859E0C93C033879CEA0F8EBB6B83" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_893091CDC77BCEEC8F50EA0F8EBB6409" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_2617EE432883CEB51D62EA0F8EBC4DE5_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_893091CDC77BCEEC8F50EA0F8EBB6409" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_2617EE432883CEB51D62EA0F8EBC4DE5_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_2617EE432883CEB51D62EA0F8EBC4DE5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_893091CDC77BCEEC8F50EA0F8EBB6409" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_2617EE432883CEB51D62EA0F8EBC4DE5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FurnitureAndFixturesMember" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_882F7A64B6EA382DF95EEA0F8EBC25B4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_2617EE432883CEB51D62EA0F8EBC4DE5" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_882F7A64B6EA382DF95EEA0F8EBC25B4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ComputerEquipmentMember" xlink:label="loc_us-gaap_ComputerEquipmentMember_24F93D0FCA209D004064EA0F8EBC5A89" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_2617EE432883CEB51D62EA0F8EBC4DE5" xlink:to="loc_us-gaap_ComputerEquipmentMember_24F93D0FCA209D004064EA0F8EBC5A89" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LeaseholdImprovementsMember" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_CEE781C46FC1C9C01810EA0F8EBC5CA3" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_2617EE432883CEB51D62EA0F8EBC4DE5" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_CEE781C46FC1C9C01810EA0F8EBC5CA3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_28D1C8403A9D6B737F5BEA0F8EBDD249" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_2A0F05F7C1B2E49AA5FDEA0F8EBD7788" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_28D1C8403A9D6B737F5BEA0F8EBDD249" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_7B741EC844C9EA43EBEEEA0F8EBD24F4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_2A0F05F7C1B2E49AA5FDEA0F8EBD7788" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_7B741EC844C9EA43EBEEEA0F8EBD24F4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_198A97508AF77B949878EA0F8EBE1DF1" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_2A0F05F7C1B2E49AA5FDEA0F8EBD7788" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_198A97508AF77B949878EA0F8EBE1DF1" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/PropertyAndEquipmentNetTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/RelatedPartyTransactions" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/RelatedPartyTransactionsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyTransactionLineItems" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_D1B4DBA2E7485B2E1F23D58B585848D6" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_69F502996097B73AB788D58B5856BB33" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_D1B4DBA2E7485B2E1F23D58B585848D6" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_69F502996097B73AB788D58B5856BB33" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_419A63F6AB5062726DD7D58B585715D8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_69F502996097B73AB788D58B5856BB33" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_419A63F6AB5062726DD7D58B585715D8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaap_RelatedPartyDomain_8D3B36B040C97FEBE3ACD58B5857D478_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_419A63F6AB5062726DD7D58B585715D8" xlink:to="loc_us-gaap_RelatedPartyDomain_8D3B36B040C97FEBE3ACD58B5857D478_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaap_RelatedPartyDomain_8D3B36B040C97FEBE3ACD58B5857D478" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_419A63F6AB5062726DD7D58B585715D8" xlink:to="loc_us-gaap_RelatedPartyDomain_8D3B36B040C97FEBE3ACD58B5857D478" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_AffiliatedEntityMember" xlink:label="loc_srt_AffiliatedEntityMember_2AAF740784A500DC8C0FD58B5857BF44" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_8D3B36B040C97FEBE3ACD58B5857D478" xlink:to="loc_srt_AffiliatedEntityMember_2AAF740784A500DC8C0FD58B5857BF44" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyTransactionAxis" xlink:label="loc_us-gaap_RelatedPartyTransactionAxis_3D73C23281945F6F269FD58B58576A5E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_69F502996097B73AB788D58B5856BB33" xlink:to="loc_us-gaap_RelatedPartyTransactionAxis_3D73C23281945F6F269FD58B58576A5E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyTransactionDomain" xlink:label="loc_us-gaap_RelatedPartyTransactionDomain_501BFC9DEC8301FC7BA0D58B5858E617_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionAxis_3D73C23281945F6F269FD58B58576A5E" xlink:to="loc_us-gaap_RelatedPartyTransactionDomain_501BFC9DEC8301FC7BA0D58B5858E617_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyTransactionDomain" xlink:label="loc_us-gaap_RelatedPartyTransactionDomain_501BFC9DEC8301FC7BA0D58B5858E617" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionAxis_3D73C23281945F6F269FD58B58576A5E" xlink:to="loc_us-gaap_RelatedPartyTransactionDomain_501BFC9DEC8301FC7BA0D58B5858E617" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_PledgeObligationMember" xlink:label="loc_bah_PledgeObligationMember_D7B7AE73E8A1C6438168D58B58583C5A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionDomain_501BFC9DEC8301FC7BA0D58B5858E617" xlink:to="loc_bah_PledgeObligationMember_D7B7AE73E8A1C6438168D58B58583C5A" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_ServicesPerformedUnderSubcontractorMember" xlink:label="loc_bah_ServicesPerformedUnderSubcontractorMember_6456F6F5E0E5BD8E860DD5DEA0817D6A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionDomain_501BFC9DEC8301FC7BA0D58B5858E617" xlink:to="loc_bah_ServicesPerformedUnderSubcontractorMember_6456F6F5E0E5BD8E860DD5DEA0817D6A" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_NumberofDirectorsAppointable" xlink:label="loc_bah_NumberofDirectorsAppointable_3644F3906A9D59167B3FD58B5859F901" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_D1B4DBA2E7485B2E1F23D58B585848D6" xlink:to="loc_bah_NumberofDirectorsAppointable_3644F3906A9D59167B3FD58B5859F901" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_NumberofDirectors" xlink:label="loc_bah_NumberofDirectors_8A9667BD7F4C403C5B08D58B58599263" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_D1B4DBA2E7485B2E1F23D58B585848D6" xlink:to="loc_bah_NumberofDirectors_8A9667BD7F4C403C5B08D58B58599263" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DueToAffiliateCurrent" xlink:label="loc_us-gaap_DueToAffiliateCurrent_0FA17CD117294AE97D75D58B58595A55" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_D1B4DBA2E7485B2E1F23D58B585848D6" xlink:to="loc_us-gaap_DueToAffiliateCurrent_0FA17CD117294AE97D75D58B58595A55" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyTransactionAmountsOfTransaction" xlink:label="loc_us-gaap_RelatedPartyTransactionAmountsOfTransaction_599E5302F69076A95D9ED58B585E59EF" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_D1B4DBA2E7485B2E1F23D58B585848D6" xlink:to="loc_us-gaap_RelatedPartyTransactionAmountsOfTransaction_599E5302F69076A95D9ED58B585E59EF" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/Revenue" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/RevenueDisaggregationOfRevenueDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_B42DA93F10328BAF45FBE0DC9A3E1EC5" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisaggregationOfRevenueTable" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_5E2160D96B8A72622A37E0DC9A37D004" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_B42DA93F10328BAF45FBE0DC9A3E1EC5" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_5E2160D96B8A72622A37E0DC9A37D004" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ContractWithCustomerBasisOfPricingAxis" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_02E0AE1AF5D8DE9EC8DDE0DC9A396013" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_5E2160D96B8A72622A37E0DC9A37D004" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_02E0AE1AF5D8DE9EC8DDE0DC9A396013" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ContractWithCustomerBasisOfPricingDomain" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_532BF10ECF538FDE2F88E0DC9A396658_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_02E0AE1AF5D8DE9EC8DDE0DC9A396013" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_532BF10ECF538FDE2F88E0DC9A396658_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ContractWithCustomerBasisOfPricingDomain" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_532BF10ECF538FDE2F88E0DC9A396658" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_02E0AE1AF5D8DE9EC8DDE0DC9A396013" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_532BF10ECF538FDE2F88E0DC9A396658" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_CostReimbursableContractMember" xlink:label="loc_bah_CostReimbursableContractMember_CCFC7C7E7DBA40D43D41E0DC9A392D25" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_532BF10ECF538FDE2F88E0DC9A396658" xlink:to="loc_bah_CostReimbursableContractMember_CCFC7C7E7DBA40D43D41E0DC9A392D25" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TimeAndMaterialsContractMember" xlink:label="loc_us-gaap_TimeAndMaterialsContractMember_CA9C9B13C7CE11D5CD1EE0DC9A3A88CD" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_532BF10ECF538FDE2F88E0DC9A396658" xlink:to="loc_us-gaap_TimeAndMaterialsContractMember_CA9C9B13C7CE11D5CD1EE0DC9A3A88CD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FixedPriceContractMember" xlink:label="loc_us-gaap_FixedPriceContractMember_EFCE5BA03D5679FE7774E0DC9A3A5BA1" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_532BF10ECF538FDE2F88E0DC9A396658" xlink:to="loc_us-gaap_FixedPriceContractMember_EFCE5BA03D5679FE7774E0DC9A3A5BA1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_StatementGeographicalAxis" xlink:label="loc_srt_StatementGeographicalAxis_07948DA3134D87B04409E0DC9A381B46" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_5E2160D96B8A72622A37E0DC9A37D004" xlink:to="loc_srt_StatementGeographicalAxis_07948DA3134D87B04409E0DC9A381B46" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srt_SegmentGeographicalDomain_B0C1B5C0D82CB55C9289E0DC9A38D6AC_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_07948DA3134D87B04409E0DC9A381B46" xlink:to="loc_srt_SegmentGeographicalDomain_B0C1B5C0D82CB55C9289E0DC9A38D6AC_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srt_SegmentGeographicalDomain_B0C1B5C0D82CB55C9289E0DC9A38D6AC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_07948DA3134D87B04409E0DC9A381B46" xlink:to="loc_srt_SegmentGeographicalDomain_B0C1B5C0D82CB55C9289E0DC9A38D6AC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_US" xlink:label="loc_country_US_0B8BC6C7971E84FD4280E0DC9A380D34" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_B0C1B5C0D82CB55C9289E0DC9A38D6AC" xlink:to="loc_country_US_0B8BC6C7971E84FD4280E0DC9A380D34" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MajorCustomersAxis" xlink:label="loc_srt_MajorCustomersAxis_1136AD211FB026DB8CBBE0DC9A3BF1E1" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_5E2160D96B8A72622A37E0DC9A37D004" xlink:to="loc_srt_MajorCustomersAxis_1136AD211FB026DB8CBBE0DC9A3BF1E1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_NameOfMajorCustomerDomain" xlink:label="loc_srt_NameOfMajorCustomerDomain_E29395F719198A208A5AE0DC9A3B60AF_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_1136AD211FB026DB8CBBE0DC9A3BF1E1" xlink:to="loc_srt_NameOfMajorCustomerDomain_E29395F719198A208A5AE0DC9A3B60AF_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_NameOfMajorCustomerDomain" xlink:label="loc_srt_NameOfMajorCustomerDomain_E29395F719198A208A5AE0DC9A3B60AF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_1136AD211FB026DB8CBBE0DC9A3BF1E1" xlink:to="loc_srt_NameOfMajorCustomerDomain_E29395F719198A208A5AE0DC9A3B60AF" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DefenseClientsMember" xlink:label="loc_bah_DefenseClientsMember_40072C6BB4AE950B2471E0DC9A3BF9D5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_E29395F719198A208A5AE0DC9A3B60AF" xlink:to="loc_bah_DefenseClientsMember_40072C6BB4AE950B2471E0DC9A3BF9D5" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_IntelligenceClientsMember" xlink:label="loc_bah_IntelligenceClientsMember_0BC257C4C29E3376E568E0DC9A3B2887" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_E29395F719198A208A5AE0DC9A3B60AF" xlink:to="loc_bah_IntelligenceClientsMember_0BC257C4C29E3376E568E0DC9A3B2887" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_CivilClientsMember" xlink:label="loc_bah_CivilClientsMember_F481A875D7FE9D192B73E0DC9A3C56DB" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_E29395F719198A208A5AE0DC9A3B60AF" xlink:to="loc_bah_CivilClientsMember_F481A875D7FE9D192B73E0DC9A3C56DB" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_GlobalCommercialClientsMember" xlink:label="loc_bah_GlobalCommercialClientsMember_6D9ED1B10F1AD70D1C73E0DC9A3C4572" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_E29395F719198A208A5AE0DC9A3B60AF" xlink:to="loc_bah_GlobalCommercialClientsMember_6D9ED1B10F1AD70D1C73E0DC9A3C4572" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ContractWithCustomerSalesChannelAxis" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelAxis_F0190268C32B69C45697E0DC9A3CFEB1" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_5E2160D96B8A72622A37E0DC9A37D004" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelAxis_F0190268C32B69C45697E0DC9A3CFEB1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ContractWithCustomerSalesChannelDomain" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_C5D9E55C1B6D493EEA89E0DC9A3C7DB8_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_F0190268C32B69C45697E0DC9A3CFEB1" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_C5D9E55C1B6D493EEA89E0DC9A3C7DB8_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ContractWithCustomerSalesChannelDomain" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_C5D9E55C1B6D493EEA89E0DC9A3C7DB8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_F0190268C32B69C45697E0DC9A3CFEB1" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_C5D9E55C1B6D493EEA89E0DC9A3C7DB8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SalesChannelDirectlyToConsumerMember" xlink:label="loc_us-gaap_SalesChannelDirectlyToConsumerMember_1BEC43881E163319467EE0DC9A3DBC27" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_C5D9E55C1B6D493EEA89E0DC9A3C7DB8" xlink:to="loc_us-gaap_SalesChannelDirectlyToConsumerMember_1BEC43881E163319467EE0DC9A3DBC27" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SalesChannelThroughIntermediaryMember" xlink:label="loc_us-gaap_SalesChannelThroughIntermediaryMember_CF9F3C25E7551ABF5474E0DC9A3D3DB9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_C5D9E55C1B6D493EEA89E0DC9A3C7DB8" xlink:to="loc_us-gaap_SalesChannelThroughIntermediaryMember_CF9F3C25E7551ABF5474E0DC9A3D3DB9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_86C669F20EFCF184F7EDE0DC9A3EF970" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_B42DA93F10328BAF45FBE0DC9A3E1EC5" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_86C669F20EFCF184F7EDE0DC9A3EF970" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_RevenueFromContractWithCustomerExcludingAssessedTaxPercentage" xlink:label="loc_bah_RevenueFromContractWithCustomerExcludingAssessedTaxPercentage_BD9428251A123244670BE0DC9A3F37C7" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_B42DA93F10328BAF45FBE0DC9A3E1EC5" xlink:to="loc_bah_RevenueFromContractWithCustomerExcludingAssessedTaxPercentage_BD9428251A123244670BE0DC9A3F37C7" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/RevenueNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_56A8DE42492D5F0734B9C6001FE7E309" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_281FA0559433D4B77AE4C6001FE6495F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_56A8DE42492D5F0734B9C6001FE7E309" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_281FA0559433D4B77AE4C6001FE6495F" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_3C2D22909038CF48BD8AC6001FE60ECD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_281FA0559433D4B77AE4C6001FE6495F" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_3C2D22909038CF48BD8AC6001FE60ECD" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_RevenueRemainingPerformanceObligationExpectedTimingofSatisfactionPeriodOne" xlink:label="loc_bah_RevenueRemainingPerformanceObligationExpectedTimingofSatisfactionPeriodOne_6B8A61280B8020721818C600201A4478" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_56A8DE42492D5F0734B9C6001FE7E309" xlink:to="loc_bah_RevenueRemainingPerformanceObligationExpectedTimingofSatisfactionPeriodOne_6B8A61280B8020721818C600201A4478" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_RevenueRemainingPerformanceObligationExpectedTimingofSatisfactionPeriodTwo" xlink:label="loc_bah_RevenueRemainingPerformanceObligationExpectedTimingofSatisfactionPeriodTwo_C111BD34C701A7FCF30CC600202CF40D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_56A8DE42492D5F0734B9C6001FE7E309" xlink:to="loc_bah_RevenueRemainingPerformanceObligationExpectedTimingofSatisfactionPeriodTwo_C111BD34C701A7FCF30CC600202CF40D" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/RevenueSummaryOfContractBalancesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/RevenueTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockBasedCompensation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockBasedCompensationScheduleOfStockOptionsGrantedDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7B2C982430B30A6F6785D5BF9E096A9D" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_BE32D905C0C0180CAEBCD5BF9E09EF75" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7B2C982430B30A6F6785D5BF9E096A9D" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_BE32D905C0C0180CAEBCD5BF9E09EF75" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaap_PlanNameAxis_0AA5289D19A2D197185AD5C0021078B3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_BE32D905C0C0180CAEBCD5BF9E09EF75" xlink:to="loc_us-gaap_PlanNameAxis_0AA5289D19A2D197185AD5C0021078B3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_35307698E3B102D162ADD5C00226D597_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_0AA5289D19A2D197185AD5C0021078B3" xlink:to="loc_us-gaap_PlanNameDomain_35307698E3B102D162ADD5C00226D597_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_35307698E3B102D162ADD5C00226D597" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_0AA5289D19A2D197185AD5C0021078B3" xlink:to="loc_us-gaap_PlanNameDomain_35307698E3B102D162ADD5C00226D597" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_AmendedAndRestatedEquityIncentivePlanMember" xlink:label="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_5C2A304D8BC757D257CBD5C03B1CEA6A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_35307698E3B102D162ADD5C00226D597" xlink:to="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_5C2A304D8BC757D257CBD5C03B1CEA6A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_AF9F8F7D53F2044771FFD5BF9E0ACD75" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7B2C982430B30A6F6785D5BF9E096A9D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_AF9F8F7D53F2044771FFD5BF9E0ACD75" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_786FDD064E5E8687095FD5BF9E0A7A94" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7B2C982430B30A6F6785D5BF9E096A9D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_786FDD064E5E8687095FD5BF9E0A7A94" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_ShareBasedCompensationArrangementbyShareBasedPaymentAwardOptionsGrantsinPeriodGrantDateFairValue" xlink:label="loc_bah_ShareBasedCompensationArrangementbyShareBasedPaymentAwardOptionsGrantsinPeriodGrantDateFairValue_370C9FB86CE3A340FDD9D5BF9E0AB146" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7B2C982430B30A6F6785D5BF9E096A9D" xlink:to="loc_bah_ShareBasedCompensationArrangementbyShareBasedPaymentAwardOptionsGrantsinPeriodGrantDateFairValue_370C9FB86CE3A340FDD9D5BF9E0AB146" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockBasedCompensationStockBasedCompensationExpenseDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_F5E688BDF8B2524CB0235290BEC1FE2D" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_FFBF349A66E45A90A3D26C4787CC3135" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_F5E688BDF8B2524CB0235290BEC1FE2D" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_FFBF349A66E45A90A3D26C4787CC3135" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_C3C286C0D9B856A18FDE26258291023D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_FFBF349A66E45A90A3D26C4787CC3135" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_C3C286C0D9B856A18FDE26258291023D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_F3632DE00ABFCDC1C274E666C33D1F91_3A03FFEE806B57A6BB951B08A10A2E36" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_C3C286C0D9B856A18FDE26258291023D" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_F3632DE00ABFCDC1C274E666C33D1F91_3A03FFEE806B57A6BB951B08A10A2E36" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_80D669593BEF56809D0840341611A888" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_C3C286C0D9B856A18FDE26258291023D" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_80D669593BEF56809D0840341611A888" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CostOfSalesMember" xlink:label="loc_us-gaap_CostOfSalesMember_C920B6B74B0958C8831759913B633719" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_80D669593BEF56809D0840341611A888" xlink:to="loc_us-gaap_CostOfSalesMember_C920B6B74B0958C8831759913B633719" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_DB8FABFF990F5C44A9825AA057101406" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_80D669593BEF56809D0840341611A888" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_DB8FABFF990F5C44A9825AA057101406" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaap_PlanNameAxis_B8AEFE993E825DAFBBDB1092EA0416A9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_FFBF349A66E45A90A3D26C4787CC3135" xlink:to="loc_us-gaap_PlanNameAxis_B8AEFE993E825DAFBBDB1092EA0416A9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_B8D11278210C778BC39CE666C33E9A33_3A03FFEE806B57A6BB951B08A10A2E36" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_B8AEFE993E825DAFBBDB1092EA0416A9" xlink:to="loc_us-gaap_PlanNameDomain_B8D11278210C778BC39CE666C33E9A33_3A03FFEE806B57A6BB951B08A10A2E36" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_BAA9414B27745F3DBCD8A7CB1270B275" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_B8AEFE993E825DAFBBDB1092EA0416A9" xlink:to="loc_us-gaap_PlanNameDomain_BAA9414B27745F3DBCD8A7CB1270B275" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_AmendedAndRestatedEquityIncentivePlanMember" xlink:label="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_93B7AD6F2187521B912970C81B2FAF8D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_BAA9414B27745F3DBCD8A7CB1270B275" xlink:to="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_93B7AD6F2187521B912970C81B2FAF8D" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_AnnualIncentivePlanMember" xlink:label="loc_bah_AnnualIncentivePlanMember_D7DA520F0F4E59D19760136E126DAA1D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_BAA9414B27745F3DBCD8A7CB1270B275" xlink:to="loc_bah_AnnualIncentivePlanMember_D7DA520F0F4E59D19760136E126DAA1D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_412D95A0CED959BFAD8932913C1A1B36" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_FFBF349A66E45A90A3D26C4787CC3135" xlink:to="loc_us-gaap_AwardTypeAxis_412D95A0CED959BFAD8932913C1A1B36" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_00CEEF24BCBC81F15C04E666C33FE820_3A03FFEE806B57A6BB951B08A10A2E36" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_412D95A0CED959BFAD8932913C1A1B36" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_00CEEF24BCBC81F15C04E666C33FE820_3A03FFEE806B57A6BB951B08A10A2E36" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_CEBACF9484E5563EABF818011E104D49" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_412D95A0CED959BFAD8932913C1A1B36" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_CEBACF9484E5563EABF818011E104D49" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_50D91833D89459FBB4C6FF5DE98B9589" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_CEBACF9484E5563EABF818011E104D49" xlink:to="loc_us-gaap_EmployeeStockOptionMember_50D91833D89459FBB4C6FF5DE98B9589" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_A2832A27FBE25AEBB79BBA72FC952428" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_CEBACF9484E5563EABF818011E104D49" xlink:to="loc_us-gaap_RestrictedStockMember_A2832A27FBE25AEBB79BBA72FC952428" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_621E0A124F5B5AB396CC760D37931C52" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_FFBF349A66E45A90A3D26C4787CC3135" xlink:to="loc_us-gaap_StatementClassOfStockAxis_621E0A124F5B5AB396CC760D37931C52" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_F4A21ED33B7AB1E3ED91E666C3408555_3A03FFEE806B57A6BB951B08A10A2E36" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_621E0A124F5B5AB396CC760D37931C52" xlink:to="loc_us-gaap_ClassOfStockDomain_F4A21ED33B7AB1E3ED91E666C3408555_3A03FFEE806B57A6BB951B08A10A2E36" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_CB53FE11309D560090F5F030A5AD5B03" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_621E0A124F5B5AB396CC760D37931C52" xlink:to="loc_us-gaap_ClassOfStockDomain_CB53FE11309D560090F5F030A5AD5B03" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonClassAMember" xlink:label="loc_us-gaap_CommonClassAMember_A9996970531D55F78E45DDD962EBE8D6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_CB53FE11309D560090F5F030A5AD5B03" xlink:to="loc_us-gaap_CommonClassAMember_A9996970531D55F78E45DDD962EBE8D6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_5F729AD8BBF25EA2AC08CD7ECC002DD5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_F5E688BDF8B2524CB0235290BEC1FE2D" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_5F729AD8BBF25EA2AC08CD7ECC002DD5" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockBasedCompensationStockOptionAndRestrictedStockAwardActivityDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94540DB7C51130F90ACDE4DF16ABBDAB" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E84A1D2B03DC58DB175FE4DF16A6AF5F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94540DB7C51130F90ACDE4DF16ABBDAB" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E84A1D2B03DC58DB175FE4DF16A6AF5F" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_B25C47BE92CAAC434452E4DF16A762A8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E84A1D2B03DC58DB175FE4DF16A6AF5F" xlink:to="loc_us-gaap_StatementClassOfStockAxis_B25C47BE92CAAC434452E4DF16A762A8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_5FEC61AED3A5931EBDBBE4DF16A72AD0_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_B25C47BE92CAAC434452E4DF16A762A8" xlink:to="loc_us-gaap_ClassOfStockDomain_5FEC61AED3A5931EBDBBE4DF16A72AD0_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_5FEC61AED3A5931EBDBBE4DF16A72AD0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_B25C47BE92CAAC434452E4DF16A762A8" xlink:to="loc_us-gaap_ClassOfStockDomain_5FEC61AED3A5931EBDBBE4DF16A72AD0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_0666CD52439A855364DBE4DF16A778F1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_5FEC61AED3A5931EBDBBE4DF16A72AD0" xlink:to="loc_us-gaap_EmployeeStockOptionMember_0666CD52439A855364DBE4DF16A778F1" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DividendTypeAxis" xlink:label="loc_bah_DividendTypeAxis_6CEBB9D6066AFD94F173E4DF16A86528" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E84A1D2B03DC58DB175FE4DF16A6AF5F" xlink:to="loc_bah_DividendTypeAxis_6CEBB9D6066AFD94F173E4DF16A86528" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DividendTypeDomain" xlink:label="loc_bah_DividendTypeDomain_45DEAF093D68E3E8D0F7E4DF16A8A13D_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_bah_DividendTypeAxis_6CEBB9D6066AFD94F173E4DF16A86528" xlink:to="loc_bah_DividendTypeDomain_45DEAF093D68E3E8D0F7E4DF16A8A13D_default" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DividendTypeDomain" xlink:label="loc_bah_DividendTypeDomain_45DEAF093D68E3E8D0F7E4DF16A8A13D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_bah_DividendTypeAxis_6CEBB9D6066AFD94F173E4DF16A86528" xlink:to="loc_bah_DividendTypeDomain_45DEAF093D68E3E8D0F7E4DF16A8A13D" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_OrdinaryCashDividendMember" xlink:label="loc_bah_OrdinaryCashDividendMember_1971B9046454802C535FE4DF16A83CD1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_DividendTypeDomain_45DEAF093D68E3E8D0F7E4DF16A8A13D" xlink:to="loc_bah_OrdinaryCashDividendMember_1971B9046454802C535FE4DF16A83CD1" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_SpecialCashDividendMember" xlink:label="loc_bah_SpecialCashDividendMember_147D308C7AFE6F89FA77E4DF16A94961" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_DividendTypeDomain_45DEAF093D68E3E8D0F7E4DF16A8A13D" xlink:to="loc_bah_SpecialCashDividendMember_147D308C7AFE6F89FA77E4DF16A94961" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaap_PlanNameAxis_530FABBB4CEEDB4D7563E4DF16A99354" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E84A1D2B03DC58DB175FE4DF16A6AF5F" xlink:to="loc_us-gaap_PlanNameAxis_530FABBB4CEEDB4D7563E4DF16A99354" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_77971BE912D1E139C004E4DF16A918D1_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_530FABBB4CEEDB4D7563E4DF16A99354" xlink:to="loc_us-gaap_PlanNameDomain_77971BE912D1E139C004E4DF16A918D1_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_77971BE912D1E139C004E4DF16A918D1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_530FABBB4CEEDB4D7563E4DF16A99354" xlink:to="loc_us-gaap_PlanNameDomain_77971BE912D1E139C004E4DF16A918D1" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_AmendedAndRestatedEquityIncentivePlanMember" xlink:label="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_0C0D8ABA3C04DC4BF718E4DF16A97260" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_77971BE912D1E139C004E4DF16A918D1" xlink:to="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_0C0D8ABA3C04DC4BF718E4DF16A97260" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_4C92AD2951A9B56EB922E4DF16AAD996" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E84A1D2B03DC58DB175FE4DF16A6AF5F" xlink:to="loc_us-gaap_AwardTypeAxis_4C92AD2951A9B56EB922E4DF16AAD996" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_AC445E73D590781DEE62E4DF16AAD7DD_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_4C92AD2951A9B56EB922E4DF16AAD996" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_AC445E73D590781DEE62E4DF16AAD7DD_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_AC445E73D590781DEE62E4DF16AAD7DD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_4C92AD2951A9B56EB922E4DF16AAD996" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_AC445E73D590781DEE62E4DF16AAD7DD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_838E2CF3EED5B71D4C19E4DF16AA2E8C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_AC445E73D590781DEE62E4DF16AAD7DD" xlink:to="loc_us-gaap_EmployeeStockOptionMember_838E2CF3EED5B71D4C19E4DF16AA2E8C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_E0575600D08A7144E1FCE4DF16AB566D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94540DB7C51130F90ACDE4DF16ABBDAB" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_E0575600D08A7144E1FCE4DF16AB566D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_4F50A0EA63E8C37A47AFE4DF16AB9B62" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_E0575600D08A7144E1FCE4DF16AB566D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_4F50A0EA63E8C37A47AFE4DF16AB9B62" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_7F5245544BFEAB1B1698E4DF16ABF9DF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_E0575600D08A7144E1FCE4DF16AB566D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_7F5245544BFEAB1B1698E4DF16ABF9DF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_0C891090474B3746D44CE4DF16ABA582" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_E0575600D08A7144E1FCE4DF16AB566D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_0C891090474B3746D44CE4DF16ABA582" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_F80DA1CDFA2FD2FBD348E4DF16AC9B35" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_E0575600D08A7144E1FCE4DF16AB566D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_F80DA1CDFA2FD2FBD348E4DF16AC9B35" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_911C6A6BFF6A46DEBD8AE4DF16AC944C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94540DB7C51130F90ACDE4DF16ABBDAB" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_911C6A6BFF6A46DEBD8AE4DF16AC944C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_2E863D170FE60CCFE680E4DF16AC8CCE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_911C6A6BFF6A46DEBD8AE4DF16AC944C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_2E863D170FE60CCFE680E4DF16AC8CCE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_962679BFFC5042D3B551E4DF16AD993A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_911C6A6BFF6A46DEBD8AE4DF16AC944C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_962679BFFC5042D3B551E4DF16AD993A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_FE55BD3A7BDEC80F9727E4DF16ADD3D5" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_911C6A6BFF6A46DEBD8AE4DF16AC944C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_FE55BD3A7BDEC80F9727E4DF16ADD3D5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_ACAB77C5DAC14286FFC2E4DF16AD263B" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_911C6A6BFF6A46DEBD8AE4DF16AC944C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_ACAB77C5DAC14286FFC2E4DF16AD263B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_88687EAF99844D6637A3E4DF16AD029B" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94540DB7C51130F90ACDE4DF16ABBDAB" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_88687EAF99844D6637A3E4DF16AD029B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_71CAA131E0642E49A251E4DF16AD266D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_88687EAF99844D6637A3E4DF16AD029B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_71CAA131E0642E49A251E4DF16AD266D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_791E66C8B056F3F0DBA9E4DF16AEC782" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_88687EAF99844D6637A3E4DF16AD029B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_791E66C8B056F3F0DBA9E4DF16AEC782" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_48BB09B1E06F93F7F2A0E4DF16AE3544" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_88687EAF99844D6637A3E4DF16AD029B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_48BB09B1E06F93F7F2A0E4DF16AE3544" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod_E8C5AD33CD15CDEEE58CE4DF16AEC325" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_88687EAF99844D6637A3E4DF16AD029B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod_E8C5AD33CD15CDEEE58CE4DF16AEC325" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_9D8287CC2943D2B250ACE4DF16AFCD39" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_88687EAF99844D6637A3E4DF16AD029B" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_9D8287CC2943D2B250ACE4DF16AFCD39" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_F4F14045AEA000532724E4DF16AF9291" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94540DB7C51130F90ACDE4DF16ABBDAB" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_F4F14045AEA000532724E4DF16AF9291" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_CAF69192ACD94BB187CCE4DF16AF5624" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_F4F14045AEA000532724E4DF16AF9291" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_CAF69192ACD94BB187CCE4DF16AF5624" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_E039B4DC406FDAAA21BDE4DF16B031B9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_F4F14045AEA000532724E4DF16AF9291" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_E039B4DC406FDAAA21BDE4DF16B031B9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_9087EDE49958689052A1E4DF16B0DC33" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_F4F14045AEA000532724E4DF16AF9291" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_9087EDE49958689052A1E4DF16B0DC33" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice_02C7D3C2ECCF7FE87282E4DF16B01ECA" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_F4F14045AEA000532724E4DF16AF9291" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice_02C7D3C2ECCF7FE87282E4DF16B01ECA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_4BC631A1789D733D98B7E4DF16B0112A" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_F4F14045AEA000532724E4DF16AF9291" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_4BC631A1789D733D98B7E4DF16B0112A" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DividendOptionExercisePriceReductionPerShare" xlink:label="loc_bah_DividendOptionExercisePriceReductionPerShare_02227BBD724C0EE47EF6E4DF16B109DA" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94540DB7C51130F90ACDE4DF16ABBDAB" xlink:to="loc_bah_DividendOptionExercisePriceReductionPerShare_02227BBD724C0EE47EF6E4DF16B109DA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockDividendsPerShareDeclared" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_190BE84CB6A240FA6FC2E4DF16B1A4A2" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94540DB7C51130F90ACDE4DF16ABBDAB" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_190BE84CB6A240FA6FC2E4DF16B1A4A2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestAbstract" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestAbstract_4BB7297CE585F8E77217E4DF16B17A87" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94540DB7C51130F90ACDE4DF16ABBDAB" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestAbstract_4BB7297CE585F8E77217E4DF16B17A87" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_CD94743F5F16C1FEF41AE4DF16B188D6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestAbstract_4BB7297CE585F8E77217E4DF16B17A87" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_CD94743F5F16C1FEF41AE4DF16B188D6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_44941C5803326B292DAEE4DF16B22002" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestAbstract_4BB7297CE585F8E77217E4DF16B17A87" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_44941C5803326B292DAEE4DF16B22002" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_EAB802A4AF54C1B1E436E4DF16B2C49C" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94540DB7C51130F90ACDE4DF16ABBDAB" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_EAB802A4AF54C1B1E436E4DF16B2C49C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue_7C6AB34E66A096AA525BE4DF16B3F668" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_EAB802A4AF54C1B1E436E4DF16B2C49C" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue_7C6AB34E66A096AA525BE4DF16B3F668" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_A6AEDC9D273E73F1B43AE4DF16B3E616" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_EAB802A4AF54C1B1E436E4DF16B2C49C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_A6AEDC9D273E73F1B43AE4DF16B3E616" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedWeightedAverageGrantDateFairValue_426B075B39490B68AB0EE4DF16B3FD24" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_EAB802A4AF54C1B1E436E4DF16B2C49C" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedWeightedAverageGrantDateFairValue_426B075B39490B68AB0EE4DF16B3FD24" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedWeightedAverageGrantDateFairValue_CC1A6954C16CC5DDCF2CE4DF16B485CE" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_EAB802A4AF54C1B1E436E4DF16B2C49C" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedWeightedAverageGrantDateFairValue_CC1A6954C16CC5DDCF2CE4DF16B485CE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_CD7D00414C2019237972E4DF16B492C6" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_94540DB7C51130F90ACDE4DF16ABBDAB" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_CD7D00414C2019237972E4DF16B492C6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_5D321775FF8CDCE94E8AE4DF16B58391" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_CD7D00414C2019237972E4DF16B492C6" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_5D321775FF8CDCE94E8AE4DF16B58391" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_8A7A88016B276825E887E4DF16B57E65" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_CD7D00414C2019237972E4DF16B492C6" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_8A7A88016B276825E887E4DF16B57E65" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_233F1A8DBE9ECDFCC9D6E4DF16B50F43" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_CD7D00414C2019237972E4DF16B492C6" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_233F1A8DBE9ECDFCC9D6E4DF16B50F43" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_12A98E4FF50E4A36DD19E4DF16B6398B" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_CD7D00414C2019237972E4DF16B492C6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_12A98E4FF50E4A36DD19E4DF16B6398B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_6DDBFA2109B9A29FF866E4DF16B6BEB5" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_CD7D00414C2019237972E4DF16B492C6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_6DDBFA2109B9A29FF866E4DF16B6BEB5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_0AD0342483D58672B2DFE4DF16B64563" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_CD7D00414C2019237972E4DF16B492C6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_0AD0342483D58672B2DFE4DF16B64563" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_7845E16E801F02C10231E4DF16B6DD81" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_CD7D00414C2019237972E4DF16B492C6" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_7845E16E801F02C10231E4DF16B6DD81" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_260F875F44342638882FE4DF16B7E2C5" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_CD7D00414C2019237972E4DF16B492C6" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_260F875F44342638882FE4DF16B7E2C5" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockBasedCompensationStockOptionAssumptionsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_24CB2710A8C756504E43DBB349571160" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_382A7EAB04D5C237DC0BDBB34954B321" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_24CB2710A8C756504E43DBB349571160" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_382A7EAB04D5C237DC0BDBB34954B321" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DividendTypeAxis" xlink:label="loc_bah_DividendTypeAxis_E82A74141E56CEE37FAFDBB349542F03" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_382A7EAB04D5C237DC0BDBB34954B321" xlink:to="loc_bah_DividendTypeAxis_E82A74141E56CEE37FAFDBB349542F03" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DividendTypeDomain" xlink:label="loc_bah_DividendTypeDomain_8F9AA2A72C06B9ABEE44DBB349542605_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_bah_DividendTypeAxis_E82A74141E56CEE37FAFDBB349542F03" xlink:to="loc_bah_DividendTypeDomain_8F9AA2A72C06B9ABEE44DBB349542605_default" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DividendTypeDomain" xlink:label="loc_bah_DividendTypeDomain_8F9AA2A72C06B9ABEE44DBB349542605" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_bah_DividendTypeAxis_E82A74141E56CEE37FAFDBB349542F03" xlink:to="loc_bah_DividendTypeDomain_8F9AA2A72C06B9ABEE44DBB349542605" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_OrdinaryCashDividendMember" xlink:label="loc_bah_OrdinaryCashDividendMember_9EBDE5AE3CA621A1096ADBB34955A948" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_DividendTypeDomain_8F9AA2A72C06B9ABEE44DBB349542605" xlink:to="loc_bah_OrdinaryCashDividendMember_9EBDE5AE3CA621A1096ADBB34955A948" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_65E5797D48F51526C8DCDBB349550A09" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_382A7EAB04D5C237DC0BDBB34954B321" xlink:to="loc_us-gaap_AwardTypeAxis_65E5797D48F51526C8DCDBB349550A09" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_C6D0D7DBCB631BB77203DBB34955293E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_65E5797D48F51526C8DCDBB349550A09" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_C6D0D7DBCB631BB77203DBB34955293E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_C6D0D7DBCB631BB77203DBB34955293E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_65E5797D48F51526C8DCDBB349550A09" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_C6D0D7DBCB631BB77203DBB34955293E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_4C69747C4D7FF4CE83DFDBB34956015B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_C6D0D7DBCB631BB77203DBB34955293E" xlink:to="loc_us-gaap_EmployeeStockOptionMember_4C69747C4D7FF4CE83DFDBB34956015B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_54CA6E30DB0F4B552553DBB349563424" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_382A7EAB04D5C237DC0BDBB34954B321" xlink:to="loc_srt_RangeAxis_54CA6E30DB0F4B552553DBB349563424" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_E9BF97CCC2F478173267DBB34956F1AA_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_54CA6E30DB0F4B552553DBB349563424" xlink:to="loc_srt_RangeMember_E9BF97CCC2F478173267DBB34956F1AA_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_E9BF97CCC2F478173267DBB34956F1AA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_54CA6E30DB0F4B552553DBB349563424" xlink:to="loc_srt_RangeMember_E9BF97CCC2F478173267DBB34956F1AA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_29B3A7AA650BDAE11EDBDBB3495786E2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_E9BF97CCC2F478173267DBB34956F1AA" xlink:to="loc_srt_MinimumMember_29B3A7AA650BDAE11EDBDBB3495786E2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_DF25296D55946F6435A5DBB34957D0F5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_E9BF97CCC2F478173267DBB34956F1AA" xlink:to="loc_srt_MaximumMember_DF25296D55946F6435A5DBB34957D0F5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockDividendsPerShareDeclared" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_6528F6A89FA013827020DBB349578020" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_24CB2710A8C756504E43DBB349571160" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_6528F6A89FA013827020DBB349578020" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_B090648EE368CF1F8ECEDBB34958F9FC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_24CB2710A8C756504E43DBB349571160" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_B090648EE368CF1F8ECEDBB34958F9FC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_3C0A9C152E2AE65EA928DBB349580E88" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_24CB2710A8C756504E43DBB349571160" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_3C0A9C152E2AE65EA928DBB349580E88" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_88B12932A705FB2DDAFADBB34958BFE4" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_24CB2710A8C756504E43DBB349571160" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_88B12932A705FB2DDAFADBB34958BFE4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_0363C21F6D2A41110079DBB3495809D3" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_24CB2710A8C756504E43DBB349571160" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_0363C21F6D2A41110079DBB3495809D3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_06BD5B5BA25DF86D3476DBB34958D147" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_24CB2710A8C756504E43DBB349571160" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_06BD5B5BA25DF86D3476DBB34958D147" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockBasedCompensationSummaryOfStockPlansDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_27009CA5DF4AFFA0BF7ED58B58E265C5" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F33EB51AC4D16382C121D58B58DC66BD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_27009CA5DF4AFFA0BF7ED58B58E265C5" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F33EB51AC4D16382C121D58B58DC66BD" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_9D38F3437EA8BFD770D3D58B58DCE078" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F33EB51AC4D16382C121D58B58DC66BD" xlink:to="loc_srt_RangeAxis_9D38F3437EA8BFD770D3D58B58DCE078" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_2E3B83E744E79BED9E8DD58B58DC14D6_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_9D38F3437EA8BFD770D3D58B58DCE078" xlink:to="loc_srt_RangeMember_2E3B83E744E79BED9E8DD58B58DC14D6_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_2E3B83E744E79BED9E8DD58B58DC14D6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_9D38F3437EA8BFD770D3D58B58DCE078" xlink:to="loc_srt_RangeMember_2E3B83E744E79BED9E8DD58B58DC14D6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_532D3B5B212B9E825115D58B58DD8AEE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_2E3B83E744E79BED9E8DD58B58DC14D6" xlink:to="loc_srt_MinimumMember_532D3B5B212B9E825115D58B58DD8AEE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_7F6AA44EBC668008410BD58B58DD5C8E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_2E3B83E744E79BED9E8DD58B58DC14D6" xlink:to="loc_srt_MaximumMember_7F6AA44EBC668008410BD58B58DD5C8E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TitleOfIndividualAxis" xlink:label="loc_us-gaap_TitleOfIndividualAxis_61913E99CC3169908CF7D58B58DDEF51" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F33EB51AC4D16382C121D58B58DC66BD" xlink:to="loc_us-gaap_TitleOfIndividualAxis_61913E99CC3169908CF7D58B58DDEF51" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_02C2B7C735A861244421D58B58DD8E94_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TitleOfIndividualAxis_61913E99CC3169908CF7D58B58DDEF51" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_02C2B7C735A861244421D58B58DD8E94_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_02C2B7C735A861244421D58B58DD8E94" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TitleOfIndividualAxis_61913E99CC3169908CF7D58B58DDEF51" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_02C2B7C735A861244421D58B58DD8E94" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OfficerMember" xlink:label="loc_us-gaap_OfficerMember_050DB1DDAD4176E2BADCD58B58DEC435" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_02C2B7C735A861244421D58B58DD8E94" xlink:to="loc_us-gaap_OfficerMember_050DB1DDAD4176E2BADCD58B58DEC435" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DirectorMember" xlink:label="loc_us-gaap_DirectorMember_9628CD1237BE0E1843FCD58B58DF80B5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_02C2B7C735A861244421D58B58DD8E94" xlink:to="loc_us-gaap_DirectorMember_9628CD1237BE0E1843FCD58B58DF80B5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaap_PlanNameAxis_241A8A53B6BEC7C52CBFD58B58DF96F6" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F33EB51AC4D16382C121D58B58DC66BD" xlink:to="loc_us-gaap_PlanNameAxis_241A8A53B6BEC7C52CBFD58B58DF96F6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_4C64CD2DBAC3B64F45FFD58B58DF7FD7_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_241A8A53B6BEC7C52CBFD58B58DF96F6" xlink:to="loc_us-gaap_PlanNameDomain_4C64CD2DBAC3B64F45FFD58B58DF7FD7_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_4C64CD2DBAC3B64F45FFD58B58DF7FD7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_241A8A53B6BEC7C52CBFD58B58DF96F6" xlink:to="loc_us-gaap_PlanNameDomain_4C64CD2DBAC3B64F45FFD58B58DF7FD7" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_AmendedAndRestatedEquityIncentivePlanMember" xlink:label="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_9B7F5D848287A1CA25DED58B58DF7FBF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_4C64CD2DBAC3B64F45FFD58B58DF7FD7" xlink:to="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_9B7F5D848287A1CA25DED58B58DF7FBF" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_AnnualIncentivePlanMember" xlink:label="loc_bah_AnnualIncentivePlanMember_1744B7096481A895C9F3D58B58E0DF94" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_4C64CD2DBAC3B64F45FFD58B58DF7FD7" xlink:to="loc_bah_AnnualIncentivePlanMember_1744B7096481A895C9F3D58B58E0DF94" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_D2E5493D6809901612C6D58B58E05F23" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F33EB51AC4D16382C121D58B58DC66BD" xlink:to="loc_us-gaap_AwardTypeAxis_D2E5493D6809901612C6D58B58E05F23" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_55135D9AB92DCC6EDEE7D58B58E01D29_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_D2E5493D6809901612C6D58B58E05F23" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_55135D9AB92DCC6EDEE7D58B58E01D29_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_55135D9AB92DCC6EDEE7D58B58E01D29" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_D2E5493D6809901612C6D58B58E05F23" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_55135D9AB92DCC6EDEE7D58B58E01D29" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_F532D9E3F71283744D6FD58B58E042DF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_55135D9AB92DCC6EDEE7D58B58E01D29" xlink:to="loc_us-gaap_EmployeeStockOptionMember_F532D9E3F71283744D6FD58B58E042DF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_11CF6A40C316F151AF9CD58B58E1E2B3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_55135D9AB92DCC6EDEE7D58B58E01D29" xlink:to="loc_us-gaap_RestrictedStockMember_11CF6A40C316F151AF9CD58B58E1E2B3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_B860EE1F16C5F8CE31E5D58B58E1D47E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_55135D9AB92DCC6EDEE7D58B58E01D29" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_B860EE1F16C5F8CE31E5D58B58E1D47E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_B97CBC25FA07371D1719D58B58E19200" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F33EB51AC4D16382C121D58B58DC66BD" xlink:to="loc_us-gaap_StatementClassOfStockAxis_B97CBC25FA07371D1719D58B58E19200" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_0A6632411FF33B501E88D58B58E1A312_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_B97CBC25FA07371D1719D58B58E19200" xlink:to="loc_us-gaap_ClassOfStockDomain_0A6632411FF33B501E88D58B58E1A312_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_0A6632411FF33B501E88D58B58E1A312" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_B97CBC25FA07371D1719D58B58E19200" xlink:to="loc_us-gaap_ClassOfStockDomain_0A6632411FF33B501E88D58B58E1A312" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonClassAMember" xlink:label="loc_us-gaap_CommonClassAMember_09F07BD20ABDA22FB9B0D58B58E2ECD1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_0A6632411FF33B501E88D58B58E1A312" xlink:to="loc_us-gaap_CommonClassAMember_09F07BD20ABDA22FB9B0D58B58E2ECD1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_8E74A98D0BC490BAE1C0D58B58E2DA7A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_27009CA5DF4AFFA0BF7ED58B58E265C5" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_8E74A98D0BC490BAE1C0D58B58E2DA7A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_241C2ED5BC4F1F073F4AD58B58E2BB99" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_27009CA5DF4AFFA0BF7ED58B58E265C5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_241C2ED5BC4F1F073F4AD58B58E2BB99" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_ShareBasedCompensationArrangementbyShareBasedPaymentAwardOptionsGrantsinPeriodGrantDateFairValue" xlink:label="loc_bah_ShareBasedCompensationArrangementbyShareBasedPaymentAwardOptionsGrantsinPeriodGrantDateFairValue_704D136A12DFBFEB620AD58B58E306B5" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_27009CA5DF4AFFA0BF7ED58B58E265C5" xlink:to="loc_bah_ShareBasedCompensationArrangementbyShareBasedPaymentAwardOptionsGrantsinPeriodGrantDateFairValue_704D136A12DFBFEB620AD58B58E306B5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_9D57342017698635BF9DD58B58E3AEDF" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_27009CA5DF4AFFA0BF7ED58B58E265C5" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_9D57342017698635BF9DD58B58E3AEDF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_1AD0F04CF49D8F090F28D58B58E3BFC5" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_27009CA5DF4AFFA0BF7ED58B58E265C5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_1AD0F04CF49D8F090F28D58B58E3BFC5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_C959DFDDEE366213DAEAD58B58E43A42" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_27009CA5DF4AFFA0BF7ED58B58E265C5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_C959DFDDEE366213DAEAD58B58E43A42" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_ShareBasedCompensationArrangementBySharebasedPaymentAwardAnnualIncentivePaymentEquityPortionIncreasePercentage" xlink:label="loc_bah_ShareBasedCompensationArrangementBySharebasedPaymentAwardAnnualIncentivePaymentEquityPortionIncreasePercentage_672980F9FED7C92F772DD58B58E42753" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_27009CA5DF4AFFA0BF7ED58B58E265C5" xlink:to="loc_bah_ShareBasedCompensationArrangementBySharebasedPaymentAwardAnnualIncentivePaymentEquityPortionIncreasePercentage_672980F9FED7C92F772DD58B58E42753" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_0B730B9109DAFA7F5C20D58B58E4D748" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_27009CA5DF4AFFA0BF7ED58B58E265C5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_0B730B9109DAFA7F5C20D58B58E4D748" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_134385D8D3ACC3F5C004D58B58E4A0CB" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_27009CA5DF4AFFA0BF7ED58B58E265C5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_134385D8D3ACC3F5C004D58B58E4A0CB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharePrice" xlink:label="loc_us-gaap_SharePrice_0F70ED1544DD85390967D58B58E40AB4" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_27009CA5DF4AFFA0BF7ED58B58E265C5" xlink:to="loc_us-gaap_SharePrice_0F70ED1544DD85390967D58B58E40AB4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockSharesAcquired" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_E7C2EE714D2CCADEFCDFD58B58E4B854" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_27009CA5DF4AFFA0BF7ED58B58E265C5" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_E7C2EE714D2CCADEFCDFD58B58E4B854" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_2982239A7236A19E951ED58B58E5C363" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_27009CA5DF4AFFA0BF7ED58B58E265C5" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_2982239A7236A19E951ED58B58E5C363" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockBasedCompensationSummaryOfUnrecognizedCompensationDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_DF96173B210B95F64F6BD58B58F3B3EE" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_58BA9C4A16E70BC4C003D58B58EF83E8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_DF96173B210B95F64F6BD58B58F3B3EE" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_58BA9C4A16E70BC4C003D58B58EF83E8" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaap_PlanNameAxis_407351B5DEA2DD00B896D58B58EF291D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_58BA9C4A16E70BC4C003D58B58EF83E8" xlink:to="loc_us-gaap_PlanNameAxis_407351B5DEA2DD00B896D58B58EF291D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_92D1EAFCEE795E4E11EED58B58F05139_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_407351B5DEA2DD00B896D58B58EF291D" xlink:to="loc_us-gaap_PlanNameDomain_92D1EAFCEE795E4E11EED58B58F05139_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_92D1EAFCEE795E4E11EED58B58F05139" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_407351B5DEA2DD00B896D58B58EF291D" xlink:to="loc_us-gaap_PlanNameDomain_92D1EAFCEE795E4E11EED58B58F05139" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_AmendedAndRestatedEquityIncentivePlanMember" xlink:label="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_17C4E6D1DD1E633B12BFD58B58F01E04" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_92D1EAFCEE795E4E11EED58B58F05139" xlink:to="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_17C4E6D1DD1E633B12BFD58B58F01E04" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_AnnualIncentivePlanMember" xlink:label="loc_bah_AnnualIncentivePlanMember_2DCE5A4EF971902F9BAAD58B58F1FA63" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_92D1EAFCEE795E4E11EED58B58F05139" xlink:to="loc_bah_AnnualIncentivePlanMember_2DCE5A4EF971902F9BAAD58B58F1FA63" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_79764885ABD163C12E08D58B58F154AA" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_58BA9C4A16E70BC4C003D58B58EF83E8" xlink:to="loc_us-gaap_AwardTypeAxis_79764885ABD163C12E08D58B58F154AA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1A63721FC6A195FCD24CD58B58F1431D_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_79764885ABD163C12E08D58B58F154AA" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1A63721FC6A195FCD24CD58B58F1431D_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1A63721FC6A195FCD24CD58B58F1431D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_79764885ABD163C12E08D58B58F154AA" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1A63721FC6A195FCD24CD58B58F1431D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_E3065DBEC359998E51F6D58B58F1B9C6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1A63721FC6A195FCD24CD58B58F1431D" xlink:to="loc_us-gaap_EmployeeStockOptionMember_E3065DBEC359998E51F6D58B58F1B9C6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_8B3735C18F668B0E9DC0D58B58F2DC58" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1A63721FC6A195FCD24CD58B58F1431D" xlink:to="loc_us-gaap_RestrictedStockMember_8B3735C18F668B0E9DC0D58B58F2DC58" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_1AB560F5E49C20202017D58B58F2C0EE" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_58BA9C4A16E70BC4C003D58B58EF83E8" xlink:to="loc_us-gaap_StatementClassOfStockAxis_1AB560F5E49C20202017D58B58F2C0EE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_EB364F31CC9C7EB3D727D58B58F20EB5_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_1AB560F5E49C20202017D58B58F2C0EE" xlink:to="loc_us-gaap_ClassOfStockDomain_EB364F31CC9C7EB3D727D58B58F20EB5_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_EB364F31CC9C7EB3D727D58B58F20EB5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_1AB560F5E49C20202017D58B58F2C0EE" xlink:to="loc_us-gaap_ClassOfStockDomain_EB364F31CC9C7EB3D727D58B58F20EB5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonClassAMember" xlink:label="loc_us-gaap_CommonClassAMember_3DE15CDE175EEFAB309ED58B58F2B8D4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_EB364F31CC9C7EB3D727D58B58F20EB5" xlink:to="loc_us-gaap_CommonClassAMember_3DE15CDE175EEFAB309ED58B58F2B8D4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_94EF5609406B1F7BD7E0D58B58F35D01" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_DF96173B210B95F64F6BD58B58F3B3EE" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_94EF5609406B1F7BD7E0D58B58F35D01" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_6F7872CFAE1908CAD301D58B58F30A27" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_DF96173B210B95F64F6BD58B58F3B3EE" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_6F7872CFAE1908CAD301D58B58F30A27" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_UnrecognizedCompensationCostNext12Months" xlink:label="loc_bah_UnrecognizedCompensationCostNext12Months_693BB22D9076E9B0E434D58B58F37CF2" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_DF96173B210B95F64F6BD58B58F3B3EE" xlink:to="loc_bah_UnrecognizedCompensationCostNext12Months_693BB22D9076E9B0E434D58B58F37CF2" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_UnrecognizedCompensationCostYearTwo" xlink:label="loc_bah_UnrecognizedCompensationCostYearTwo_F268EE1B6C80F96480D2D58B58F480DA" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_DF96173B210B95F64F6BD58B58F3B3EE" xlink:to="loc_bah_UnrecognizedCompensationCostYearTwo_F268EE1B6C80F96480D2D58B58F480DA" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_UnrecognizedCompensationCostYearThree" xlink:label="loc_bah_UnrecognizedCompensationCostYearThree_AE4D54D5383DA0FC997DD58B58F4AD5A" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_DF96173B210B95F64F6BD58B58F3B3EE" xlink:to="loc_bah_UnrecognizedCompensationCostYearThree_AE4D54D5383DA0FC997DD58B58F4AD5A" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_UnrecognizedCompensationCostYearFour" xlink:label="loc_bah_UnrecognizedCompensationCostYearFour_2CE0ACFA00ABA558557ED58B58F44203" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_DF96173B210B95F64F6BD58B58F3B3EE" xlink:to="loc_bah_UnrecognizedCompensationCostYearFour_2CE0ACFA00ABA558557ED58B58F44203" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_UnrecognizedCompensationCostYearFive" xlink:label="loc_bah_UnrecognizedCompensationCostYearFive_E98C2B3EDAE57DA36165D58B58F45CF4" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_DF96173B210B95F64F6BD58B58F3B3EE" xlink:to="loc_bah_UnrecognizedCompensationCostYearFive_E98C2B3EDAE57DA36165D58B58F45CF4" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockBasedCompensationTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockholdersEquity" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockholdersEquityNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_DCA76AD8CDAB7BD5B0C9C5DEDBC01EF6" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_598817699A39B6CA2BCEC5DEDBBE276D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_DCA76AD8CDAB7BD5B0C9C5DEDBC01EF6" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_598817699A39B6CA2BCEC5DEDBBE276D" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaap_PlanNameAxis_1611194C6E8F8E28C47AC5DEDBBFC4DC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_598817699A39B6CA2BCEC5DEDBBE276D" xlink:to="loc_us-gaap_PlanNameAxis_1611194C6E8F8E28C47AC5DEDBBFC4DC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_F608E6C85A0EFCF873D5C5DEDBBF4CCC_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_1611194C6E8F8E28C47AC5DEDBBFC4DC" xlink:to="loc_us-gaap_PlanNameDomain_F608E6C85A0EFCF873D5C5DEDBBF4CCC_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_F608E6C85A0EFCF873D5C5DEDBBF4CCC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_1611194C6E8F8E28C47AC5DEDBBFC4DC" xlink:to="loc_us-gaap_PlanNameDomain_F608E6C85A0EFCF873D5C5DEDBBF4CCC" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_EmployeeStockPurchasePlanMember" xlink:label="loc_bah_EmployeeStockPurchasePlanMember_5B71315C9A0891974F80C5DEDBBFAB23" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_F608E6C85A0EFCF873D5C5DEDBBF4CCC" xlink:to="loc_bah_EmployeeStockPurchasePlanMember_5B71315C9A0891974F80C5DEDBBFAB23" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_CF0F51B92827C4FC3B1CC5DEDBC0DFB6" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_598817699A39B6CA2BCEC5DEDBBE276D" xlink:to="loc_us-gaap_StatementClassOfStockAxis_CF0F51B92827C4FC3B1CC5DEDBC0DFB6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_6990C7875A3F767459A1C5DEDBC04B8F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_CF0F51B92827C4FC3B1CC5DEDBC0DFB6" xlink:to="loc_us-gaap_ClassOfStockDomain_6990C7875A3F767459A1C5DEDBC04B8F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_6990C7875A3F767459A1C5DEDBC04B8F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_CF0F51B92827C4FC3B1CC5DEDBC0DFB6" xlink:to="loc_us-gaap_ClassOfStockDomain_6990C7875A3F767459A1C5DEDBC04B8F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonClassAMember" xlink:label="loc_us-gaap_CommonClassAMember_CC93A3341E3B33041829C5DEDBC0A3BC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_6990C7875A3F767459A1C5DEDBC04B8F" xlink:to="loc_us-gaap_CommonClassAMember_CC93A3341E3B33041829C5DEDBC0A3BC" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_CommonStockVotesPerShare" xlink:label="loc_bah_CommonStockVotesPerShare_3FCAB32555F1C12D0CB7C5DEDBC0A410" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_DCA76AD8CDAB7BD5B0C9C5DEDBC01EF6" xlink:to="loc_bah_CommonStockVotesPerShare_3FCAB32555F1C12D0CB7C5DEDBC0A410" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_AF4CE3AABE2C03501225C5DEDBC17EAF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_DCA76AD8CDAB7BD5B0C9C5DEDBC01EF6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_AF4CE3AABE2C03501225C5DEDBC17EAF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPricePurchaseDate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPricePurchaseDate_2D6E0BEC458ABB6D73D7C5DEDBC1EDC6" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_DCA76AD8CDAB7BD5B0C9C5DEDBC01EF6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPricePurchaseDate_2D6E0BEC458ABB6D73D7C5DEDBC1EDC6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_5DCA9822C90D83E41C57C5DEDBC1C67C" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_DCA76AD8CDAB7BD5B0C9C5DEDBC01EF6" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_5DCA9822C90D83E41C57C5DEDBC1C67C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockRepurchaseProgramAuthorizedAmount1" xlink:label="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_785A64CB2FD8EDA0776DC5DEDBC10B66" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_DCA76AD8CDAB7BD5B0C9C5DEDBC01EF6" xlink:to="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_785A64CB2FD8EDA0776DC5DEDBC10B66" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockSharesAcquired" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_145097B675BA69A96A2EC5DEDBC2373B" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_DCA76AD8CDAB7BD5B0C9C5DEDBC01EF6" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_145097B675BA69A96A2EC5DEDBC2373B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_6359A9D5F6348218FFF3C5DEDBC26BD2" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_DCA76AD8CDAB7BD5B0C9C5DEDBC01EF6" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_6359A9D5F6348218FFF3C5DEDBC26BD2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_04CE7B974673D9350F91C5DEDBC22246" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_DCA76AD8CDAB7BD5B0C9C5DEDBC01EF6" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_04CE7B974673D9350F91C5DEDBC22246" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockholdersEquitySummaryOfDividendsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D5FD14464573438F4817C5DEDBBA73CF" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E0B49CACB04843C6D652C5DEDBB9265A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D5FD14464573438F4817C5DEDBBA73CF" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E0B49CACB04843C6D652C5DEDBB9265A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DividendTypeAxis" xlink:label="loc_bah_DividendTypeAxis_4A5ED9CDB50F47C5C521C5DEDBB99370" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E0B49CACB04843C6D652C5DEDBB9265A" xlink:to="loc_bah_DividendTypeAxis_4A5ED9CDB50F47C5C521C5DEDBB99370" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DividendTypeDomain" xlink:label="loc_bah_DividendTypeDomain_4845700C086B94A1F534C5DEDBB9DD5C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_bah_DividendTypeAxis_4A5ED9CDB50F47C5C521C5DEDBB99370" xlink:to="loc_bah_DividendTypeDomain_4845700C086B94A1F534C5DEDBB9DD5C_default" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DividendTypeDomain" xlink:label="loc_bah_DividendTypeDomain_4845700C086B94A1F534C5DEDBB9DD5C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_bah_DividendTypeAxis_4A5ED9CDB50F47C5C521C5DEDBB99370" xlink:to="loc_bah_DividendTypeDomain_4845700C086B94A1F534C5DEDBB9DD5C" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DividendequivalentMember" xlink:label="loc_bah_DividendequivalentMember_C65F8C884722DA3971B6C5DEDBBABDF6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_DividendTypeDomain_4845700C086B94A1F534C5DEDBB9DD5C" xlink:to="loc_bah_DividendequivalentMember_C65F8C884722DA3971B6C5DEDBBABDF6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DividendsCommonStock" xlink:label="loc_us-gaap_DividendsCommonStock_CD7ECF42D763950F2445C666E41BC54E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D5FD14464573438F4817C5DEDBBA73CF" xlink:to="loc_us-gaap_DividendsCommonStock_CD7ECF42D763950F2445C666E41BC54E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Dividends" xlink:label="loc_us-gaap_Dividends_19E579AF0FDEE0AD9C8BC5DEDBBA3903" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D5FD14464573438F4817C5DEDBBA73CF" xlink:to="loc_us-gaap_Dividends_19E579AF0FDEE0AD9C8BC5DEDBBA3903" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockholdersEquityTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/SubsequentEvents" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/SubsequentEventsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventLineItems" xlink:label="loc_us-gaap_SubsequentEventLineItems_F49269F15BE974FACA61EAFC834A6FBD" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTable" xlink:label="loc_us-gaap_SubsequentEventTable_D670AD07C65B166D9E2CEAFC8344EBB0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_F49269F15BE974FACA61EAFC834A6FBD" xlink:to="loc_us-gaap_SubsequentEventTable_D670AD07C65B166D9E2CEAFC8344EBB0" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_BDC471656496B0165A1DEAFC834493E1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_D670AD07C65B166D9E2CEAFC8344EBB0" xlink:to="loc_us-gaap_AwardTypeAxis_BDC471656496B0165A1DEAFC834493E1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6FF8DFAEA4F7BE7CC1DBEAFC83458522_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_BDC471656496B0165A1DEAFC834493E1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6FF8DFAEA4F7BE7CC1DBEAFC83458522_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6FF8DFAEA4F7BE7CC1DBEAFC83458522" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_BDC471656496B0165A1DEAFC834493E1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6FF8DFAEA4F7BE7CC1DBEAFC83458522" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_68CB5F3AFAE4363ABD27EAFC83450680" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6FF8DFAEA4F7BE7CC1DBEAFC83458522" xlink:to="loc_us-gaap_RestrictedStockMember_68CB5F3AFAE4363ABD27EAFC83450680" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_2DAC0830FD4B6F59A76BEAFC8346BEF2" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_D670AD07C65B166D9E2CEAFC8344EBB0" xlink:to="loc_us-gaap_StatementClassOfStockAxis_2DAC0830FD4B6F59A76BEAFC8346BEF2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_3C8A117F35329D5BEF14EAFC834616E0_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_2DAC0830FD4B6F59A76BEAFC8346BEF2" xlink:to="loc_us-gaap_ClassOfStockDomain_3C8A117F35329D5BEF14EAFC834616E0_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_3C8A117F35329D5BEF14EAFC834616E0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_2DAC0830FD4B6F59A76BEAFC8346BEF2" xlink:to="loc_us-gaap_ClassOfStockDomain_3C8A117F35329D5BEF14EAFC834616E0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonClassAMember" xlink:label="loc_us-gaap_CommonClassAMember_85770632762DE8383A03EAFC8346686F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_3C8A117F35329D5BEF14EAFC834616E0" xlink:to="loc_us-gaap_CommonClassAMember_85770632762DE8383A03EAFC8346686F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_E672570E1250C2BC4261EAFC83468802" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_D670AD07C65B166D9E2CEAFC8344EBB0" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_E672570E1250C2BC4261EAFC83468802" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_2894E14DAE279FF7CE2BEAFC8347B503_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_E672570E1250C2BC4261EAFC83468802" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_2894E14DAE279FF7CE2BEAFC8347B503_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_2894E14DAE279FF7CE2BEAFC8347B503" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_E672570E1250C2BC4261EAFC83468802" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_2894E14DAE279FF7CE2BEAFC8347B503" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_CFF65F51EA87FA8063AAEAFC8347305B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_2894E14DAE279FF7CE2BEAFC8347B503" xlink:to="loc_us-gaap_InterestRateSwapMember_CFF65F51EA87FA8063AAEAFC8347305B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationAxis" xlink:label="loc_us-gaap_HedgingDesignationAxis_875F7810393D629EBBBAEAFC83478259" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_D670AD07C65B166D9E2CEAFC8344EBB0" xlink:to="loc_us-gaap_HedgingDesignationAxis_875F7810393D629EBBBAEAFC83478259" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_257CCB5950DEF7F32160EAFC83478EC5_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_875F7810393D629EBBBAEAFC83478259" xlink:to="loc_us-gaap_HedgingDesignationDomain_257CCB5950DEF7F32160EAFC83478EC5_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_257CCB5950DEF7F32160EAFC83478EC5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_875F7810393D629EBBBAEAFC83478259" xlink:to="loc_us-gaap_HedgingDesignationDomain_257CCB5950DEF7F32160EAFC83478EC5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DesignatedAsHedgingInstrumentMember" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_E1158EB7D9E1894D3FF3EAFC83487181" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_257CCB5950DEF7F32160EAFC83478EC5" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_E1158EB7D9E1894D3FF3EAFC83487181" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_1E1069CC0A2CA2BFE990EAFC83486AA2" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_D670AD07C65B166D9E2CEAFC8344EBB0" xlink:to="loc_us-gaap_DebtInstrumentAxis_1E1069CC0A2CA2BFE990EAFC83486AA2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_3D4D1D3D404749B3DEF5EAFC8348B232_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_1E1069CC0A2CA2BFE990EAFC83486AA2" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_3D4D1D3D404749B3DEF5EAFC8348B232_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_3D4D1D3D404749B3DEF5EAFC8348B232" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_1E1069CC0A2CA2BFE990EAFC83486AA2" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_3D4D1D3D404749B3DEF5EAFC8348B232" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DelayedDrawFacilityMember" xlink:label="loc_bah_DelayedDrawFacilityMember_B57CDF3AA037701C2505EAFC8348A242" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_3D4D1D3D404749B3DEF5EAFC8348B232" xlink:to="loc_bah_DelayedDrawFacilityMember_B57CDF3AA037701C2505EAFC8348A242" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_B891F14F7EA34B2B5434EAFC83496AED" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_D670AD07C65B166D9E2CEAFC8344EBB0" xlink:to="loc_srt_RangeAxis_B891F14F7EA34B2B5434EAFC83496AED" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_766D36A21C7E237F89C5EAFC83492E6A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_B891F14F7EA34B2B5434EAFC83496AED" xlink:to="loc_srt_RangeMember_766D36A21C7E237F89C5EAFC83492E6A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_766D36A21C7E237F89C5EAFC83492E6A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_B891F14F7EA34B2B5434EAFC83496AED" xlink:to="loc_srt_RangeMember_766D36A21C7E237F89C5EAFC83492E6A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_5CDC1ADE1FBB6BEDFC54EAFC83494DF4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_766D36A21C7E237F89C5EAFC83492E6A" xlink:to="loc_srt_MinimumMember_5CDC1ADE1FBB6BEDFC54EAFC83494DF4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_4EEE717DA23139802729EAFC83491EFD" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_766D36A21C7E237F89C5EAFC83492E6A" xlink:to="loc_srt_MaximumMember_4EEE717DA23139802729EAFC83491EFD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_6B0FCED75863B64C7E32EAFC834A6066" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_D670AD07C65B166D9E2CEAFC8344EBB0" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_6B0FCED75863B64C7E32EAFC834A6066" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_DCCE94B95FB8015303E1EAFC834A36F1_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_6B0FCED75863B64C7E32EAFC834A6066" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_DCCE94B95FB8015303E1EAFC834A36F1_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_DCCE94B95FB8015303E1EAFC834A36F1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_6B0FCED75863B64C7E32EAFC834A6066" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_DCCE94B95FB8015303E1EAFC834A36F1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember_4E2423B8D3C60C770C84EAFC834A9346" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_DCCE94B95FB8015303E1EAFC834A36F1" xlink:to="loc_us-gaap_SubsequentEventMember_4E2423B8D3C60C770C84EAFC834A9346" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DerivativesNumberOfAgreementsEnteredIntoDuringThePeriod" xlink:label="loc_bah_DerivativesNumberOfAgreementsEnteredIntoDuringThePeriod_5F3337C9DF94EC4AFF4DEAFC834A6B29" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_F49269F15BE974FACA61EAFC834A6FBD" xlink:to="loc_bah_DerivativesNumberOfAgreementsEnteredIntoDuringThePeriod_5F3337C9DF94EC4AFF4DEAFC834A6B29" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_DerivativesNumberOfFinancialInstitutions" xlink:label="loc_bah_DerivativesNumberOfFinancialInstitutions_420766B84C907FEA2ED9EAFC834BA105" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_F49269F15BE974FACA61EAFC834A6FBD" xlink:to="loc_bah_DerivativesNumberOfFinancialInstitutions_420766B84C907FEA2ED9EAFC834BA105" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_DerivativeNotionalAmount" xlink:label="loc_invest_DerivativeNotionalAmount_72CE2579A5BCE7617529EAFC834B0A35" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_F49269F15BE974FACA61EAFC834A6FBD" xlink:to="loc_invest_DerivativeNotionalAmount_72CE2579A5BCE7617529EAFC834B0A35" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeFixedInterestRate" xlink:label="loc_us-gaap_DerivativeFixedInterestRate_EC9259D7501261B0EBA2EAFC834B5B41" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_F49269F15BE974FACA61EAFC834A6FBD" xlink:to="loc_us-gaap_DerivativeFixedInterestRate_EC9259D7501261B0EBA2EAFC834B5B41" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromLinesOfCredit" xlink:label="loc_us-gaap_ProceedsFromLinesOfCredit_622E7EA3606BC2522B8DEAFC834B1B7D" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_F49269F15BE974FACA61EAFC834A6FBD" xlink:to="loc_us-gaap_ProceedsFromLinesOfCredit_622E7EA3606BC2522B8DEAFC834B1B7D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_9A6B80A25A8816CD0BADEAFC834BCC83" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_F49269F15BE974FACA61EAFC834A6FBD" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_9A6B80A25A8816CD0BADEAFC834BCC83" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_85E3B8F700EDF80A2111EAFC834C94D3" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_F49269F15BE974FACA61EAFC834A6FBD" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_85E3B8F700EDF80A2111EAFC834C94D3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_215CAF65F1FC07BDF3C7EAFC834CBB10" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_F49269F15BE974FACA61EAFC834A6FBD" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_215CAF65F1FC07BDF3C7EAFC834CBB10" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockDividendsPerShareDeclared" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_E906B46F9257AB21443BEAFC834CD74D" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_F49269F15BE974FACA61EAFC834A6FBD" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_E906B46F9257AB21443BEAFC834CD74D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockRepurchaseProgramAuthorizedAmount1" xlink:label="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_4883FE4CED03C1423437EAFC834C47F9" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_F49269F15BE974FACA61EAFC834A6FBD" xlink:to="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_4883FE4CED03C1423437EAFC834C47F9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_A53B8FDB8D29283B7968EAFC834C0C9F" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_F49269F15BE974FACA61EAFC834A6FBD" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_A53B8FDB8D29283B7968EAFC834C0C9F" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/SummaryOfSignificantAccountingPolicies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/SummaryOfSignificantAccountingPoliciesIntangibleAssetsAndGoodwillDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_6172C00C5E8F234C20AAC5D99B8613A0" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_72D54B12FFAFA8FD1BE4C5D99B84827E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_6172C00C5E8F234C20AAC5D99B8613A0" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_72D54B12FFAFA8FD1BE4C5D99B84827E" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_30703769EDCBDCBDA5BCC5D99B84DEF0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_72D54B12FFAFA8FD1BE4C5D99B84827E" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_30703769EDCBDCBDA5BCC5D99B84DEF0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_418049BA25C9E363135DC5D99B841A2A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_30703769EDCBDCBDA5BCC5D99B84DEF0" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_418049BA25C9E363135DC5D99B841A2A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_418049BA25C9E363135DC5D99B841A2A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_30703769EDCBDCBDA5BCC5D99B84DEF0" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_418049BA25C9E363135DC5D99B841A2A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="loc_us-gaap_CustomerRelationshipsMember_67A3FA47F5C7EACC1D96C5D99B856032" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_418049BA25C9E363135DC5D99B841A2A" xlink:to="loc_us-gaap_CustomerRelationshipsMember_67A3FA47F5C7EACC1D96C5D99B856032" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SoftwareAndSoftwareDevelopmentCostsMember" xlink:label="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_CAE7F28FD58EF58979A5C5D99B854510" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_418049BA25C9E363135DC5D99B841A2A" xlink:to="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_CAE7F28FD58EF58979A5C5D99B854510" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_A006E6F8264CAB470341C5D99B8548F9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_72D54B12FFAFA8FD1BE4C5D99B84827E" xlink:to="loc_srt_RangeAxis_A006E6F8264CAB470341C5D99B8548F9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_086F16A2A7246D62A8D9C5D99B857B41_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_A006E6F8264CAB470341C5D99B8548F9" xlink:to="loc_srt_RangeMember_086F16A2A7246D62A8D9C5D99B857B41_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_086F16A2A7246D62A8D9C5D99B857B41" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_A006E6F8264CAB470341C5D99B8548F9" xlink:to="loc_srt_RangeMember_086F16A2A7246D62A8D9C5D99B857B41" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_31BDE1D56EC5DBACDD3DC5D99B86A24C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_086F16A2A7246D62A8D9C5D99B857B41" xlink:to="loc_srt_MinimumMember_31BDE1D56EC5DBACDD3DC5D99B86A24C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_9912F2CA731AF6B41AE0C5D99B86D790" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_086F16A2A7246D62A8D9C5D99B857B41" xlink:to="loc_srt_MaximumMember_9912F2CA731AF6B41AE0C5D99B86D790" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_0DE9A0B710F043966CA0C5D99B86FDAB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_6172C00C5E8F234C20AAC5D99B8613A0" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_0DE9A0B710F043966CA0C5D99B86FDAB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ImpairmentOfIntangibleAssetsFinitelived" xlink:label="loc_us-gaap_ImpairmentOfIntangibleAssetsFinitelived_A3CC7ACF820868301D20C5D99B864000" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_6172C00C5E8F234C20AAC5D99B8613A0" xlink:to="loc_us-gaap_ImpairmentOfIntangibleAssetsFinitelived_A3CC7ACF820868301D20C5D99B864000" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GoodwillImpairmentLoss" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_B9888C904B7F55D8DD56C5D99B87D535" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_6172C00C5E8F234C20AAC5D99B8613A0" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_B9888C904B7F55D8DD56C5D99B87D535" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/SummaryOfSignificantAccountingPoliciesPropertyPlantAndEquipmentDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4796DEB073BEFC278A45EA0F8F5FEA7C" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_E138FBF189F4F7B37D95EA0F8F5DA3B6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4796DEB073BEFC278A45EA0F8F5FEA7C" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_E138FBF189F4F7B37D95EA0F8F5DA3B6" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_07476902EEEB9AA47733EA0F8F5DFD2F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_E138FBF189F4F7B37D95EA0F8F5DA3B6" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_07476902EEEB9AA47733EA0F8F5DFD2F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_CD3FBF16C135C65B405BEA0F8F5DF1D1_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_07476902EEEB9AA47733EA0F8F5DFD2F" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_CD3FBF16C135C65B405BEA0F8F5DF1D1_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_CD3FBF16C135C65B405BEA0F8F5DF1D1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_07476902EEEB9AA47733EA0F8F5DFD2F" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_CD3FBF16C135C65B405BEA0F8F5DF1D1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FurnitureAndFixturesMember" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_3CA744D871E440428EF9EA0F8F5E150D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_CD3FBF16C135C65B405BEA0F8F5DF1D1" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_3CA744D871E440428EF9EA0F8F5E150D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ComputerEquipmentMember" xlink:label="loc_us-gaap_ComputerEquipmentMember_A336E8090CD22C2BB0F4EA0F8F5EB6C4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_CD3FBF16C135C65B405BEA0F8F5DF1D1" xlink:to="loc_us-gaap_ComputerEquipmentMember_A336E8090CD22C2BB0F4EA0F8F5EB6C4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_A13CABE761E4318250CDEA0F8F5E64D5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_E138FBF189F4F7B37D95EA0F8F5DA3B6" xlink:to="loc_srt_RangeAxis_A13CABE761E4318250CDEA0F8F5E64D5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_4F468DA3B91032CD22FFEA0F8F5FC9EF_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_A13CABE761E4318250CDEA0F8F5E64D5" xlink:to="loc_srt_RangeMember_4F468DA3B91032CD22FFEA0F8F5FC9EF_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_4F468DA3B91032CD22FFEA0F8F5FC9EF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_A13CABE761E4318250CDEA0F8F5E64D5" xlink:to="loc_srt_RangeMember_4F468DA3B91032CD22FFEA0F8F5FC9EF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_B14097F5421682CB79A3EA0F8F5F842C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_4F468DA3B91032CD22FFEA0F8F5FC9EF" xlink:to="loc_srt_MinimumMember_B14097F5421682CB79A3EA0F8F5F842C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_96BCD0AA925F0FDAA920EA0F8F5FF09E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_4F468DA3B91032CD22FFEA0F8F5FC9EF" xlink:to="loc_srt_MaximumMember_96BCD0AA925F0FDAA920EA0F8F5FF09E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_27BF28B833912603511FEA0F8F5F4D8D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4796DEB073BEFC278A45EA0F8F5FEA7C" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_27BF28B833912603511FEA0F8F5F4D8D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ImpairmentOfLongLivedAssetsHeldForUse" xlink:label="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_7F3AF9E562ACA7C59519EA0F8F60C0FC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4796DEB073BEFC278A45EA0F8F5FEA7C" xlink:to="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_7F3AF9E562ACA7C59519EA0F8F60C0FC" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/SummaryOfSignificantAccountingPoliciesRecentAccountingPronouncementsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_063C3F87648D57C274BBE5A8987F0B03" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_DA8E854793DD501CD55DE5A8987C584A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_063C3F87648D57C274BBE5A8987F0B03" xlink:to="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_DA8E854793DD501CD55DE5A8987C584A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RestatementAxis" xlink:label="loc_srt_RestatementAxis_E872DA3BAEF6D13E5DE6E5A8987CA237" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_DA8E854793DD501CD55DE5A8987C584A" xlink:to="loc_srt_RestatementAxis_E872DA3BAEF6D13E5DE6E5A8987CA237" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RestatementDomain" xlink:label="loc_srt_RestatementDomain_9E123A80351ECB2CE060E5A8987C5DD3_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RestatementAxis_E872DA3BAEF6D13E5DE6E5A8987CA237" xlink:to="loc_srt_RestatementDomain_9E123A80351ECB2CE060E5A8987C5DD3_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RestatementDomain" xlink:label="loc_srt_RestatementDomain_9E123A80351ECB2CE060E5A8987C5DD3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RestatementAxis_E872DA3BAEF6D13E5DE6E5A8987CA237" xlink:to="loc_srt_RestatementDomain_9E123A80351ECB2CE060E5A8987C5DD3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RestatementAdjustmentMember" xlink:label="loc_srt_RestatementAdjustmentMember_F280B3D410F1110C7E45E5A8987D2D11" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RestatementDomain_9E123A80351ECB2CE060E5A8987C5DD3" xlink:to="loc_srt_RestatementAdjustmentMember_F280B3D410F1110C7E45E5A8987D2D11" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_ABA9EA5B1B1566959336E5A8987D6789" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_DA8E854793DD501CD55DE5A8987C584A" xlink:to="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_ABA9EA5B1B1566959336E5A8987D6789" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_D207BECE9C1206EEC575E5A8987D4117_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_ABA9EA5B1B1566959336E5A8987D6789" xlink:to="loc_us-gaap_TypeOfAdoptionMember_D207BECE9C1206EEC575E5A8987D4117_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_D207BECE9C1206EEC575E5A8987D4117" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_ABA9EA5B1B1566959336E5A8987D6789" xlink:to="loc_us-gaap_TypeOfAdoptionMember_D207BECE9C1206EEC575E5A8987D4117" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountingStandardsUpdate201409Member" xlink:label="loc_us-gaap_AccountingStandardsUpdate201409Member_AEE1718B8BCDA5E65955E5A8987D6D6A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfAdoptionMember_D207BECE9C1206EEC575E5A8987D4117" xlink:to="loc_us-gaap_AccountingStandardsUpdate201409Member_AEE1718B8BCDA5E65955E5A8987D6D6A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountingStandardsUpdate201602Member" xlink:label="loc_us-gaap_AccountingStandardsUpdate201602Member_F7B8868EE421A4215D73E5A8987E160A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfAdoptionMember_D207BECE9C1206EEC575E5A8987D4117" xlink:to="loc_us-gaap_AccountingStandardsUpdate201602Member_F7B8868EE421A4215D73E5A8987E160A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_E5EB2663D4E6CC4EDA3FE5A8987E0AA3" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_DA8E854793DD501CD55DE5A8987C584A" xlink:to="loc_us-gaap_StatementScenarioAxis_E5EB2663D4E6CC4EDA3FE5A8987E0AA3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_2A033CD5B686B02D52EFE5A8987E8F49_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_E5EB2663D4E6CC4EDA3FE5A8987E0AA3" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_2A033CD5B686B02D52EFE5A8987E8F49_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_2A033CD5B686B02D52EFE5A8987E8F49" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_E5EB2663D4E6CC4EDA3FE5A8987E0AA3" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_2A033CD5B686B02D52EFE5A8987E8F49" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioForecastMember" xlink:label="loc_us-gaap_ScenarioForecastMember_BB93CFA2D22140B6E5DFE5A8987F2F9A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScenarioUnspecifiedDomain_2A033CD5B686B02D52EFE5A8987E8F49" xlink:to="loc_us-gaap_ScenarioForecastMember_BB93CFA2D22140B6E5DFE5A8987F2F9A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_7A2C94FE419C6891285DE5A8987FB895" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_063C3F87648D57C274BBE5A8987F0B03" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_7A2C94FE419C6891285DE5A8987FB895" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CumulativeEffectOnRetainedEarningsNetOfTax1" xlink:label="loc_us-gaap_CumulativeEffectOnRetainedEarningsNetOfTax1_52262EF1E5C22A0A042FE5A8987F2592" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_063C3F87648D57C274BBE5A8987F0B03" xlink:to="loc_us-gaap_CumulativeEffectOnRetainedEarningsNetOfTax1_52262EF1E5C22A0A042FE5A8987F2592" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAsset" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_D187C9334718AFA7274CE5A8987F9910" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_063C3F87648D57C274BBE5A8987F0B03" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_D187C9334718AFA7274CE5A8987F9910" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseLiability" xlink:label="loc_us-gaap_OperatingLeaseLiability_B12D21FF18042B6B3CA5E5A980AAE3DB" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_063C3F87648D57C274BBE5A8987F0B03" xlink:to="loc_us-gaap_OperatingLeaseLiability_B12D21FF18042B6B3CA5E5A980AAE3DB" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/SummaryOfSignificantAccountingPoliciesScheduleOfEffectOfAdoptionDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_52735EA40DADBE569156C5E4CC983EEF" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_566FF1B5C7DAFAE5A3E4C5E4CC978C74" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_52735EA40DADBE569156C5E4CC983EEF" xlink:to="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_566FF1B5C7DAFAE5A3E4C5E4CC978C74" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_C8374A577814A0FB554CC5E61928904F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_566FF1B5C7DAFAE5A3E4C5E4CC978C74" xlink:to="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_C8374A577814A0FB554CC5E61928904F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_FE232A9782A30448F617C5E6192E2EDC_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_C8374A577814A0FB554CC5E61928904F" xlink:to="loc_us-gaap_TypeOfAdoptionMember_FE232A9782A30448F617C5E6192E2EDC_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_FE232A9782A30448F617C5E6192E2EDC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_C8374A577814A0FB554CC5E61928904F" xlink:to="loc_us-gaap_TypeOfAdoptionMember_FE232A9782A30448F617C5E6192E2EDC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountingStandardsUpdate201409Member" xlink:label="loc_us-gaap_AccountingStandardsUpdate201409Member_E5F8A099B21079038BD3C5E61A3CE04B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfAdoptionMember_FE232A9782A30448F617C5E6192E2EDC" xlink:to="loc_us-gaap_AccountingStandardsUpdate201409Member_E5F8A099B21079038BD3C5E61A3CE04B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountingStandardsUpdate201707Member" xlink:label="loc_us-gaap_AccountingStandardsUpdate201707Member_7E96A1BDF3AD5B538B59C5E61EB9BA5A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfAdoptionMember_FE232A9782A30448F617C5E6192E2EDC" xlink:to="loc_us-gaap_AccountingStandardsUpdate201707Member_7E96A1BDF3AD5B538B59C5E61EB9BA5A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RestatementAxis" xlink:label="loc_srt_RestatementAxis_EB3A4A1E6EC0001DFE50C5E614FDB565" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_566FF1B5C7DAFAE5A3E4C5E4CC978C74" xlink:to="loc_srt_RestatementAxis_EB3A4A1E6EC0001DFE50C5E614FDB565" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RestatementDomain" xlink:label="loc_srt_RestatementDomain_C4C7B102961925A1FEEEC5E87B0EDC43_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RestatementAxis_EB3A4A1E6EC0001DFE50C5E614FDB565" xlink:to="loc_srt_RestatementDomain_C4C7B102961925A1FEEEC5E87B0EDC43_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RestatementDomain" xlink:label="loc_srt_RestatementDomain_C4C7B102961925A1FEEEC5E87B0EDC43" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RestatementAxis_EB3A4A1E6EC0001DFE50C5E614FDB565" xlink:to="loc_srt_RestatementDomain_C4C7B102961925A1FEEEC5E87B0EDC43" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ScenarioPreviouslyReportedMember" xlink:label="loc_srt_ScenarioPreviouslyReportedMember_0D1466E1F39988B00F0FC5E615C81C76" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RestatementDomain_C4C7B102961925A1FEEEC5E87B0EDC43" xlink:to="loc_srt_ScenarioPreviouslyReportedMember_0D1466E1F39988B00F0FC5E615C81C76" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RestatementAdjustmentMember" xlink:label="loc_srt_RestatementAdjustmentMember_EE0A05B18FEFD463AC5BC5E618AC86B5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RestatementDomain_C4C7B102961925A1FEEEC5E87B0EDC43" xlink:to="loc_srt_RestatementAdjustmentMember_EE0A05B18FEFD463AC5BC5E618AC86B5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_46D14D074AA1A1B56E5CC5E4DFA3AB8C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_52735EA40DADBE569156C5E4CC983EEF" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_46D14D074AA1A1B56E5CC5E4DFA3AB8C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_90FA593813276AF582AEC5E4DF7BF91E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_52735EA40DADBE569156C5E4CC983EEF" xlink:to="loc_us-gaap_OperatingIncomeLoss_90FA593813276AF582AEC5E4DF7BF91E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_EF842CE443660971A651C5E4DF3E3725" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_52735EA40DADBE569156C5E4CC983EEF" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_EF842CE443660971A651C5E4DF3E3725" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_769DF75C43935468013BC5E4DF60CFCD" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_52735EA40DADBE569156C5E4CC983EEF" xlink:to="loc_us-gaap_NetIncomeLoss_769DF75C43935468013BC5E4DF60CFCD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EarningsPerShareBasic" xlink:label="loc_us-gaap_EarningsPerShareBasic_993A532E49699D9BBD2AC5E4DF2952C5" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_52735EA40DADBE569156C5E4CC983EEF" xlink:to="loc_us-gaap_EarningsPerShareBasic_993A532E49699D9BBD2AC5E4DF2952C5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EarningsPerShareDiluted" xlink:label="loc_us-gaap_EarningsPerShareDiluted_24E8AF2C52FDC29050A2C5E4DF4F3FD7" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_52735EA40DADBE569156C5E4CC983EEF" xlink:to="loc_us-gaap_EarningsPerShareDiluted_24E8AF2C52FDC29050A2C5E4DF4F3FD7" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/SummaryOfSignificantAccountingPoliciesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/SupplementalFinancialInformation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/SupplementalFinancialInformationDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ValuationAndQualifyingAccountsDisclosureLineItems" xlink:label="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems_17EE6543311C98D385EBC1E3E2D45623" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ValuationAndQualifyingAccountsDisclosureTable" xlink:label="loc_srt_ValuationAndQualifyingAccountsDisclosureTable_814BDFFDA6555403E5ADC1E3E2CF2896" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems_17EE6543311C98D385EBC1E3E2D45623" xlink:to="loc_srt_ValuationAndQualifyingAccountsDisclosureTable_814BDFFDA6555403E5ADC1E3E2CF2896" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ValuationAllowancesAndReservesTypeAxis" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_40FE6A0676DEC1A938D9C1E3E2D02C3E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureTable_814BDFFDA6555403E5ADC1E3E2CF2896" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_40FE6A0676DEC1A938D9C1E3E2D02C3E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDomain" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDomain_ED7A7EAA5D9F6528E0B8C1E3E2D14934_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_40FE6A0676DEC1A938D9C1E3E2D02C3E" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDomain_ED7A7EAA5D9F6528E0B8C1E3E2D14934_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDomain" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDomain_ED7A7EAA5D9F6528E0B8C1E3E2D14934" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_40FE6A0676DEC1A938D9C1E3E2D02C3E" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDomain_ED7A7EAA5D9F6528E0B8C1E3E2D14934" xlink:type="arc" />
    <link:loc xlink:href="bah-20190331.xsd#bah_SECSchedule1209ValuationAllowanceAccountsReceivableMember" xlink:label="loc_bah_SECSchedule1209ValuationAllowanceAccountsReceivableMember_846E8281DD2ABEFEEB9DC1E70388203C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesDomain_ED7A7EAA5D9F6528E0B8C1E3E2D14934" xlink:to="loc_bah_SECSchedule1209ValuationAllowanceAccountsReceivableMember_846E8281DD2ABEFEEB9DC1E70388203C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember" xlink:label="loc_us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember_06BE7E6B0933D2A5D8C5C1E3E2D230FB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesDomain_ED7A7EAA5D9F6528E0B8C1E3E2D14934" xlink:to="loc_us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember_06BE7E6B0933D2A5D8C5C1E3E2D230FB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MovementInValuationAllowancesAndReservesRollForward" xlink:label="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_C0084710F196CC494B40C1E3E2D4AFF4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems_17EE6543311C98D385EBC1E3E2D45623" xlink:to="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_C0084710F196CC494B40C1E3E2D4AFF4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ValuationAllowancesAndReservesBalance" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesBalance_0707EED118B758B0FB1AC1E3E2D4F350" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_C0084710F196CC494B40C1E3E2D4AFF4" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesBalance_0707EED118B758B0FB1AC1E3E2D4F350" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense_3F9CFB1B581360EF8406C1E3E2D456A5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_C0084710F196CC494B40C1E3E2D4AFF4" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense_3F9CFB1B581360EF8406C1E3E2D456A5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDeductions" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDeductions_CA423045009F1FD57859C1E3E2D567FB" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_C0084710F196CC494B40C1E3E2D4AFF4" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDeductions_CA423045009F1FD57859C1E3E2D567FB" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/SupplementalFinancialInformationTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/UnauditedQuarterlyFinancialData" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/UnauditedQuarterlyFinancialDataDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/UnauditedQuarterlyFinancialDataTables" xlink:type="extended" />
</link:linkbase>
