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  <xs:element id="sigi_SelectiveInsuranceCompanyOfSouthCarolinaMember" abstract="true" name="SelectiveInsuranceCompanyOfSouthCarolinaMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_BorrowingsFromSubsidiaries" abstract="false" name="BorrowingsFromSubsidiaries" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_TotalLeasesDueInThreeYears" abstract="false" name="TotalLeasesDueInThreeYears" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_ScheduleofTypesofShareBasedPaymentsIssuedTableTextBlock" abstract="false" name="ScheduleofTypesofShareBasedPaymentsIssuedTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="sigi_PersonalAutomobileMember" abstract="true" name="PersonalAutomobileMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_DividendsPaidToParentAxis" abstract="true" name="DividendsPaidToParentAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="sigi_PaymentsToAcquireCommercialMortgageLoans" abstract="false" name="PaymentsToAcquireCommercialMortgageLoans" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_TerrorismRiskInsuranceProgramReimbursedPercentageMaximum" abstract="false" name="TerrorismRiskInsuranceProgramReimbursedPercentageMaximum" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="sigi_ReinsuranceRecoverableDomain" abstract="true" name="ReinsuranceRecoverableDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_IncreaseInDPWFromPriorYear" abstract="false" name="IncreaseInDPWFromPriorYear" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="sigi_PeriodchangeunrealizedgainslossesinOCI" abstract="false" name="PeriodchangeunrealizedgainslossesinOCI" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="sigi_AllowanceforCreditLossesAxis" abstract="true" name="AllowanceforCreditLossesAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="sigi_DividendsPaidToParentDomain" abstract="true" name="DividendsPaidToParentDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_COVID19Member" abstract="true" name="COVID19Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_FundedStatusOfRetirementIncomePlanDomain" abstract="true" name="FundedStatusOfRetirementIncomePlanDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_SupplementalLeaseInformationTableTextBlock" abstract="false" name="SupplementalLeaseInformationTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
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  <xs:element id="sigi_DeferredTaxAssetsUnrealizedLossesOnSecuritiesGross" abstract="false" name="DeferredTaxAssetsUnrealizedLossesOnSecuritiesGross" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_Omnibus2005StockPlanMember" abstract="true" name="Omnibus2005StockPlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_ProceedsFromPreferredStockOfferingLessIssuanceCostsAxis" abstract="true" name="ProceedsFromPreferredStockOfferingLessIssuanceCostsAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
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  <xs:element id="sigi_ScheduleOfFairValueAndGrossPreTaxUnrealizedUnrecognizedLossOfSecuritiesByLengthOfTimeAxis" abstract="true" name="ScheduleOfFairValueAndGrossPreTaxUnrealizedUnrecognizedLossOfSecuritiesByLengthOfTimeAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="sigi_ChangeinHistoricalClaimRateExperienceMember" abstract="true" name="ChangeinHistoricalClaimRateExperienceMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_BusinessOwnersPoliciesMember" abstract="true" name="BusinessOwnersPoliciesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_NarrativeAbstract" abstract="true" name="NarrativeAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="sigi_FloodCededPremiumsAndLossesAxis" abstract="true" name="FloodCededPremiumsAndLossesAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="sigi_RelatedPartyTransactionsContributionsToFoundation" abstract="false" name="RelatedPartyTransactionsContributionsToFoundation" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="sigi_DebtSecuritiesAvailableForSaleCreditLossExpense" abstract="false" name="DebtSecuritiesAvailableForSaleCreditLossExpense" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="sigi_ReturnonEquity" abstract="false" name="ReturnonEquity" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="sigi_InvestmentCommitmentsTableTextBlock" abstract="false" name="InvestmentCommitmentsTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
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  <xs:element id="sigi_PercentageOfNetUnsecuredReinsurance" abstract="false" name="PercentageOfNetUnsecuredReinsurance" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="sigi_AMBestRatedReinsurerMember" abstract="true" name="AMBestRatedReinsurerMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_ZeroPointSeventyEightPercentBorrowingfromFHLBNYDueSeptember142020.Member" abstract="true" name="ZeroPointSeventyEightPercentBorrowingfromFHLBNYDueSeptember142020.Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_MaturitiesofLeaseLiabilitiesAbstract" abstract="true" name="MaturitiesofLeaseLiabilitiesAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="sigi_UnrealizedGainLossOnInvestmentsDomain" abstract="true" name="UnrealizedGainLossOnInvestmentsDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_LesseeDisclosureTextBlock" abstract="false" name="LesseeDisclosureTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="sigi_CommercialPersonalAutomobileMember" abstract="true" name="CommercialPersonalAutomobileMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_SelectiveInsuranceCompanyOfNewEnglandMember" abstract="true" name="SelectiveInsuranceCompanyOfNewEnglandMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_TotalUnrealizedGainsLossesOnInvestmentSecuritiesGross" abstract="false" name="TotalUnrealizedGainsLossesOnInvestmentSecuritiesGross" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_PreferredStockSharesIssuedSIGI" abstract="false" name="PreferredStockSharesIssuedSIGI" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="sigi_NewJerseyDividendRestriction" abstract="false" name="NewJerseyDividendRestriction" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="sigi_AllowanceForUncollectiblePremiumsReceivableTable" abstract="true" name="AllowanceForUncollectiblePremiumsReceivableTable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType"/>
  <xs:element id="sigi_AFSFixedIncomeSecuritiesMember" abstract="true" name="AFSFixedIncomeSecuritiesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_OnePointEightyOnePercentBorrowingFromFederalHomeLoanBankDueFebruary182020Member" abstract="true" name="OnePointEightyOnePercentBorrowingFromFederalHomeLoanBankDueFebruary182020Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
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  <xs:element id="sigi_LongTermDebtExcludingIssuanceCostsMember" abstract="true" name="LongTermDebtExcludingIssuanceCostsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_LossesOnInvestmentSecuritiesForWhichWeHaveTheIntentToSell" abstract="false" name="LossesOnInvestmentSecuritiesForWhichWeHaveTheIntentToSell" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_PrincipalPaymentsOfBorrowingsFromSubsidiaries" abstract="false" name="PrincipalPaymentsOfBorrowingsFromSubsidiaries" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_IntercompanyNotesPayable" abstract="false" name="IntercompanyNotesPayable" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_ScheduleofShareBasedCompensationSharesAuthorizedAvailableforIssuanceandOutstandingTableTextBlock" abstract="false" name="ScheduleofShareBasedCompensationSharesAuthorizedAvailableforIssuanceandOutstandingTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
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  <xs:element id="sigi_ProceedsFromEquityInvestmentsInExcessOfCurrentYearEarnings" abstract="false" name="ProceedsFromEquityInvestmentsInExcessOfCurrentYearEarnings" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_IncreaseDecreaseInUnearnedPremiumsNetOfPrepaidReinsurance" abstract="false" name="IncreaseDecreaseInUnearnedPremiumsNetOfPrepaidReinsurance" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="sigi_SelectiveAutoInsuranceCompanyOfNewJerseyMember" abstract="true" name="SelectiveAutoInsuranceCompanyOfNewJerseyMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_PercentageOfUnpaidNfipClaimsCededByFederalGovernment" abstract="false" name="PercentageOfUnpaidNfipClaimsCededByFederalGovernment" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="sigi_PrincipalAccelerationAmountStateofDefault" abstract="false" name="PrincipalAccelerationAmountStateofDefault" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_RemainingUnsecuredReinsuranceMember" abstract="true" name="RemainingUnsecuredReinsuranceMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_DebtAndEquitySecuritiesRealizedGains" abstract="false" name="DebtAndEquitySecuritiesRealizedGains" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_FinanceleaseobligationMember" abstract="true" name="FinanceleaseobligationMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_AgentStockPurchasePlanMember" abstract="true" name="AgentStockPurchasePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_DebtSecuritiesAvailableforsaleAllowanceforCreditLossNet" abstract="false" name="DebtSecuritiesAvailableforsaleAllowanceforCreditLossNet" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="sigi_FinanceLeaseLiabilityNotYetCommenced" abstract="false" name="FinanceLeaseLiabilityNotYetCommenced" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_DividendRestrictionNewYork" abstract="false" name="DividendRestrictionNewYork" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="sigi_DisclosureofShareBasedCompensationExpensesAbstract" abstract="true" name="DisclosureofShareBasedCompensationExpensesAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="sigi_HanoverRuckversicherungsAgMember" abstract="true" name="HanoverRuckversicherungsAgMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_InterestPaidOperatingandInvestingActivities" abstract="false" name="InterestPaidOperatingandInvestingActivities" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_ContractualObligationAdditionalInvestmentinAlternativeorOtherInvestments" abstract="false" name="ContractualObligationAdditionalInvestmentinAlternativeorOtherInvestments" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_PremiumsReceivableAllowanceNetOfWriteoffs" abstract="false" name="PremiumsReceivableAllowanceNetOfWriteoffs" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_DeferredTaxLiabilitiesInvestmentSecuritiesUnrealizedGain" abstract="false" name="DeferredTaxLiabilitiesInvestmentSecuritiesUnrealizedGain" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_TotalFederalAndStatePoolsMember" abstract="true" name="TotalFederalAndStatePoolsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_ScheduleofShareBasedCompensationESPPandASPPSharesIssuedTableTextBlock" abstract="false" name="ScheduleofShareBasedCompensationESPPandASPPSharesIssuedTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="sigi_ScheduleOfAggregatedSummarizedIncomeStatementFinancialInformationForPartnerhipsInOurAlternativeInvestmentPortfolioTableTextBlock" abstract="false" name="ScheduleOfAggregatedSummarizedIncomeStatementFinancialInformationForPartnerhipsInOurAlternativeInvestmentPortfolioTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="sigi_ConversionOfAFSFixedIncomeSecuritiesToEquitySecurities" abstract="false" name="ConversionOfAFSFixedIncomeSecuritiesToEquitySecurities" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_DisclosureofRetiredPlansAbstract" abstract="true" name="DisclosureofRetiredPlansAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="sigi_TotalLeasesDueInTwoYears" abstract="false" name="TotalLeasesDueInTwoYears" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_UnrealizedGainLossonEquitySecuritiesSold" abstract="false" name="UnrealizedGainLossonEquitySecuritiesSold" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_SelectiveInsuranceCompanyOfNewYorkMember" abstract="true" name="SelectiveInsuranceCompanyOfNewYorkMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_CommercialMortgageLoanFairValue" abstract="false" name="CommercialMortgageLoanFairValue" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_FloodCededPremiumsAndLossesTable" abstract="true" name="FloodCededPremiumsAndLossesTable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType"/>
  <xs:element id="sigi_AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleTax" abstract="false" name="AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleTax" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_TotalLeasesDueInFourYears" abstract="false" name="TotalLeasesDueInFourYears" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_TotalLeasesDueThereafter" abstract="false" name="TotalLeasesDueThereafter" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="sigi_TotalSegmentIncomeLossFromContinuingOperationsBeforeFederalIncomeTax" abstract="false" name="TotalSegmentIncomeLossFromContinuingOperationsBeforeFederalIncomeTax" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="sigi_TransatlanticReinsuranceCompanyMember" abstract="true" name="TransatlanticReinsuranceCompanyMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_RealizedGainsLossesOfEquityMethodInvestees" abstract="false" name="RealizedGainsLossesOfEquityMethodInvestees" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="sigi_EquityImpactOnCumulativeEffectAdjustment" abstract="false" name="EquityImpactOnCumulativeEffectAdjustment" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="sigi_ChangeinDefinedBenefitPlanDiscountRate" abstract="false" name="ChangeinDefinedBenefitPlanDiscountRate" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_FinanceLeaseExpense" abstract="false" name="FinanceLeaseExpense" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_TerrorismRiskInsuranceProgramCompanysEstimatedDeductible" abstract="false" name="TerrorismRiskInsuranceProgramCompanysEstimatedDeductible" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="sigi_TotalInvestmentRevenues" abstract="false" name="TotalInvestmentRevenues" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_DebtSecuritiesAvailableforsaleAllowanceforCreditLossGross" abstract="false" name="DebtSecuritiesAvailableforsaleAllowanceforCreditLossGross" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="sigi_ChangeinNetDeferredFederalIncomeTaxAssets" abstract="false" name="ChangeinNetDeferredFederalIncomeTaxAssets" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="sigi_IncomeTaxReconciliationTaxAdvantagedInterestIncome" abstract="false" name="IncomeTaxReconciliationTaxAdvantagedInterestIncome" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sigi_OperatingLeaseLiabilityNotYetCommenced" abstract="false" name="OperatingLeaseLiabilityNotYetCommenced" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="sigi_ScheduleOfFloodCededPremiumsAndLossesTableTextBlock" abstract="false" name="ScheduleOfFloodCededPremiumsAndLossesTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
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  <xs:element id="sigi_SelectiveFireAndCasualtyInsuranceCompanyMember" abstract="true" name="SelectiveFireAndCasualtyInsuranceCompanyMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sigi_AggregatedSummarizedFinancialInformationForPartnershipsInOurAlternativeInvestmentPortfolioTable" abstract="true" name="AggregatedSummarizedFinancialInformationForPartnershipsInOurAlternativeInvestmentPortfolioTable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType"/>
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  <xs:element id="sigi_AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleBeforeTax" abstract="false" name="AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleBeforeTax" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="sigi_PurchaseAmountOfAnnuities" abstract="false" name="PurchaseAmountOfAnnuities" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="sigi_EnvironmentalclaimsMember" abstract="true" name="EnvironmentalclaimsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
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  <xs:element id="sigi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsEmployeeStockPurchasePlanGrantsInPeriodWeightedAverageGrantDateFairValueTotal" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsEmployeeStockPurchasePlanGrantsInPeriodWeightedAverageGrantDateFairValueTotal" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:perShareItemType"/>
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  <xs:element id="sigi_LandfillSitesRelatedClaimsMember" abstract="true" name="LandfillSitesRelatedClaimsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
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  <xs:element id="sigi_LiabilityForAsbestosAndEnvironmentalClaimsNetPaymentForClaimsSIGI" abstract="false" name="LiabilityForAsbestosAndEnvironmentalClaimsNetPaymentForClaimsSIGI" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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</xs:schema>
