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<link:definition>1009 - Disclosure - Revenue from Contracts with Customers</link:definition>
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<link:definition>1010 - Disclosure - Business Combinations</link:definition>
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<link:definition>1011 - Disclosure - Goodwill and Other Intangible Assets, net</link:definition>
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<link:definition>1012 - Disclosure - Leases</link:definition>
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<link:definition>1013 - Disclosure - Commitments and Contingencies</link:definition>
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<link:definition>1014 - Disclosure - Employee Benefit Plan</link:definition>
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<link:definition>1015 - Disclosure - Stock-Based Compensation</link:definition>
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<link:definition>1016 - Disclosure - Credit Facility</link:definition>
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<link:definition>1017 - Disclosure - Income Taxes</link:definition>
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<link:definition>1018 - Disclosure - Derivative Instruments and Hedging Activities</link:definition>
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<link:definition>1019 - Disclosure - Fair Value Measurements</link:definition>
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<link:definition>1020 - Disclosure - Shareholders' Equity</link:definition>
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<link:definition>1021 - Disclosure - Earnings Per Share</link:definition>
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<link:usedOn>link:definitionLink</link:usedOn>
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<link:definition>1022 - Disclosure - Business Segments and Geographic Information</link:definition>
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<link:usedOn>link:definitionLink</link:usedOn>
<link:usedOn>link:calculationLink</link:usedOn>
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<link:definition>1023 - Disclosure - Recently Issued Accounting Standards</link:definition>
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<link:usedOn>link:definitionLink</link:usedOn>
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<link:roleType roleURI="http://www.mastech.com/role/DescriptionOfBusinessAndBasisOfPresentationPolicies" id="DescriptionOfBusinessAndBasisOfPresentationPolicies">
<link:definition>1024 - Disclosure - Description of Business and Basis of Presentation (Policies)</link:definition>
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<link:definition>1025 - Disclosure - Revenue from Contracts with Customers (Tables)</link:definition>
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<link:roleType roleURI="http://www.mastech.com/role/BusinessCombinationsTables" id="BusinessCombinationsTables">
<link:definition>1026 - Disclosure - Business Combinations (Tables)</link:definition>
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<link:usedOn>link:definitionLink</link:usedOn>
<link:usedOn>link:calculationLink</link:usedOn>
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<link:roleType roleURI="http://www.mastech.com/role/GoodwillAndOtherIntangibleAssetsNetTables" id="GoodwillAndOtherIntangibleAssetsNetTables">
<link:definition>1027 - Disclosure - Goodwill and Other Intangible Assets, net (Tables)</link:definition>
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<link:usedOn>link:definitionLink</link:usedOn>
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<link:definition>1028 - Disclosure - Leases (Tables)</link:definition>
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<link:definition>1029 - Disclosure - Income Taxes (Tables)</link:definition>
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<link:roleType roleURI="http://www.mastech.com/role/DerivativeInstrumentsAndHedgingActivitiesTables" id="DerivativeInstrumentsAndHedgingActivitiesTables">
<link:definition>1030 - Disclosure - Derivative Instruments and Hedging Activities (Tables)</link:definition>
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<link:usedOn>link:definitionLink</link:usedOn>
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<link:definition>1031 - Disclosure - Fair Value Measurements (Tables)</link:definition>
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<link:roleType roleURI="http://www.mastech.com/role/BusinessSegmentsAndGeographicInformationTables" id="BusinessSegmentsAndGeographicInformationTables">
<link:definition>1032 - Disclosure - Business Segments and Geographic Information (Tables)</link:definition>
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<link:definition>1033 - Disclosure - Revenue from Contracts with Customers - Additional Information (Detail)</link:definition>
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<link:definition>1034 - Disclosure - Revenue from Contracts with Customers - Summary of Disaggregation of Our Revenues by Contract Type and Operating Segment (Detail)</link:definition>
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<link:usedOn>link:definitionLink</link:usedOn>
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<link:definition>1035 - Disclosure - Revenue from Contracts with Customers - Summary of Revenue from External Customers (Detail)</link:definition>
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<link:usedOn>link:definitionLink</link:usedOn>
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<link:roleType roleURI="http://www.mastech.com/role/BusinessCombinationsAdditionalInformationDetail" id="BusinessCombinationsAdditionalInformationDetail">
<link:definition>1036 - Disclosure - Business Combinations - Additional Information (Detail)</link:definition>
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<link:usedOn>link:definitionLink</link:usedOn>
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<link:definition>1037 - Disclosure - Business Combinations - Summary of Fair Value of Consideration for Acquired Business (Detail)</link:definition>
<link:usedOn>link:presentationLink</link:usedOn>
<link:usedOn>link:definitionLink</link:usedOn>
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<link:roleType roleURI="http://www.mastech.com/role/BusinessCombinationsSummaryOfFairValueOfConsiderationForAcquiredBusinessParentheticalDetail" id="BusinessCombinationsSummaryOfFairValueOfConsiderationForAcquiredBusinessParentheticalDetail">
<link:definition>1038 - Disclosure - Business Combinations - Summary of Fair Value of Consideration for Acquired Business (Parenthetical) (Detail)</link:definition>
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<link:roleType roleURI="http://www.mastech.com/role/BusinessCombinationsSummaryOfSourceOfFundsDetail" id="BusinessCombinationsSummaryOfSourceOfFundsDetail">
<link:definition>1039 - Disclosure - Business Combinations - Summary of Source of Funds (Detail)</link:definition>
<link:usedOn>link:presentationLink</link:usedOn>
<link:usedOn>link:definitionLink</link:usedOn>
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<link:definition>1040 - Disclosure - Business Combinations - Schedule of Valuation of Net Assets Acquired (Detail)</link:definition>
<link:usedOn>link:presentationLink</link:usedOn>
<link:usedOn>link:definitionLink</link:usedOn>
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<link:definition>1041 - Disclosure - Business Combinations - Summary of Unaudited Pro Forma Results (Detail)</link:definition>
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<link:usedOn>link:definitionLink</link:usedOn>
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<link:definition>1042 - Disclosure - Goodwill and Other Intangible Assets, net - Additional Information (Detail)</link:definition>
<link:usedOn>link:presentationLink</link:usedOn>
<link:usedOn>link:definitionLink</link:usedOn>
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<link:definition>1043 - Disclosure - Goodwill and Other Intangible Assets - Components of Identifiable Intangible assets (Detail)</link:definition>
<link:usedOn>link:presentationLink</link:usedOn>
<link:usedOn>link:definitionLink</link:usedOn>
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<link:definition>1044 - Disclosure - Goodwill and Other Intangible Assets, net - Schedule of Estimated Amortization Expense (Detail)</link:definition>
<link:usedOn>link:presentationLink</link:usedOn>
<link:usedOn>link:definitionLink</link:usedOn>
<link:usedOn>link:calculationLink</link:usedOn>
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<link:roleType roleURI="http://www.mastech.com/role/LeasesAdditionalInformationDetail" id="LeasesAdditionalInformationDetail">
<link:definition>1045 - Disclosure - Leases - Additional Information (Detail)</link:definition>
<link:usedOn>link:presentationLink</link:usedOn>
<link:usedOn>link:definitionLink</link:usedOn>
<link:usedOn>link:calculationLink</link:usedOn>
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<link:roleType roleURI="http://www.mastech.com/role/LeasesSummaryOfBalanceSheetClassificationOfLeaseAssetAndRelatedLeaseLiabilityDetail" id="LeasesSummaryOfBalanceSheetClassificationOfLeaseAssetAndRelatedLeaseLiabilityDetail">
<link:definition>1046 - Disclosure - Leases - Summary of Balance Sheet classification of lease asset and related lease liability (Detail)</link:definition>
<link:usedOn>link:presentationLink</link:usedOn>
<link:usedOn>link:definitionLink</link:usedOn>
<link:usedOn>link:calculationLink</link:usedOn>
</link:roleType>
<link:roleType roleURI="http://www.mastech.com/role/LeasesScheduleOfFutureMinimumRentalPaymentsForOperatingLeasesDetail" id="LeasesScheduleOfFutureMinimumRentalPaymentsForOperatingLeasesDetail">
<link:definition>1047 - Disclosure - Leases - Schedule of Future Minimum Rental Payments for Operating Leases (Detail)</link:definition>
<link:usedOn>link:presentationLink</link:usedOn>
<link:usedOn>link:definitionLink</link:usedOn>
<link:usedOn>link:calculationLink</link:usedOn>
</link:roleType>
<link:roleType roleURI="http://www.mastech.com/role/EmployeeBenefitPlanAdditionalInformationDetail" id="EmployeeBenefitPlanAdditionalInformationDetail">
<link:definition>1048 - Disclosure - Employee Benefit Plan - Additional Information (Detail)</link:definition>
<link:usedOn>link:presentationLink</link:usedOn>
<link:usedOn>link:definitionLink</link:usedOn>
<link:usedOn>link:calculationLink</link:usedOn>
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<link:roleType roleURI="http://www.mastech.com/role/StockBasedCompensationAdditionalInformationDetail" id="StockBasedCompensationAdditionalInformationDetail">
<link:definition>1049 - Disclosure - Stock-Based Compensation - Additional Information (Detail)</link:definition>
<link:usedOn>link:presentationLink</link:usedOn>
<link:usedOn>link:definitionLink</link:usedOn>
<link:usedOn>link:calculationLink</link:usedOn>
</link:roleType>
<link:roleType roleURI="http://www.mastech.com/role/CreditFacilityAdditionalInformationDetail" id="CreditFacilityAdditionalInformationDetail">
<link:definition>1050 - Disclosure - Credit Facility - Additional information (Detail)</link:definition>
<link:usedOn>link:presentationLink</link:usedOn>
<link:usedOn>link:definitionLink</link:usedOn>
<link:usedOn>link:calculationLink</link:usedOn>
</link:roleType>
<link:roleType roleURI="http://www.mastech.com/role/IncomeTaxesComponentsOfIncomeBeforeIncomeTaxesDetail" id="IncomeTaxesComponentsOfIncomeBeforeIncomeTaxesDetail">
<link:definition>1051 - Disclosure - Income Taxes - Components of Income Before Income Taxes (Detail)</link:definition>
<link:usedOn>link:presentationLink</link:usedOn>
<link:usedOn>link:definitionLink</link:usedOn>
<link:usedOn>link:calculationLink</link:usedOn>
</link:roleType>
<link:roleType roleURI="http://www.mastech.com/role/IncomeTaxesProvisionForIncomeTaxesDetail" id="IncomeTaxesProvisionForIncomeTaxesDetail">
<link:definition>1052 - Disclosure - Income Taxes - Provision for Income Taxes (Detail)</link:definition>
<link:usedOn>link:presentationLink</link:usedOn>
<link:usedOn>link:definitionLink</link:usedOn>
<link:usedOn>link:calculationLink</link:usedOn>
</link:roleType>
<link:roleType roleURI="http://www.mastech.com/role/IncomeTaxesReconciliationOfIncomeTaxesDetail" id="IncomeTaxesReconciliationOfIncomeTaxesDetail">
<link:definition>1053 - Disclosure - Income Taxes - Reconciliation of Income Taxes (Detail)</link:definition>
<link:usedOn>link:presentationLink</link:usedOn>
<link:usedOn>link:definitionLink</link:usedOn>
<link:usedOn>link:calculationLink</link:usedOn>
</link:roleType>
<link:roleType roleURI="http://www.mastech.com/role/IncomeTaxesAdditionalInformationDetail" id="IncomeTaxesAdditionalInformationDetail">
<link:definition>1054 - Disclosure - Income Taxes - Additional Information (Detail)</link:definition>
<link:usedOn>link:presentationLink</link:usedOn>
<link:usedOn>link:definitionLink</link:usedOn>
<link:usedOn>link:calculationLink</link:usedOn>
</link:roleType>
<link:roleType roleURI="http://www.mastech.com/role/DerivativeInstrumentsAndHedgingActivitiesAdditionalInformationDetail" id="DerivativeInstrumentsAndHedgingActivitiesAdditionalInformationDetail">
<link:definition>1055 - Disclosure - Derivative Instruments and Hedging Activities - Additional Information (Detail)</link:definition>
<link:usedOn>link:presentationLink</link:usedOn>
<link:usedOn>link:definitionLink</link:usedOn>
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