﻿<?xml version="1.0" encoding="utf-8"?>
<Return xmlns="http://www.irs.gov/efile" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.irs.gov/efile" returnVersion="2024v5.5">
  <ReturnHeader binaryAttachmentCnt="0">
    <ReturnTs>2026-02-23T08:39:02-06:00</ReturnTs>
    <TaxPeriodEndDt>2025-06-30</TaxPeriodEndDt>
    <PreparerFirmGrp>
      <PreparerFirmEIN>362985770</PreparerFirmEIN>
      <PreparerFirmName>
        <BusinessNameLine1Txt>SELDEN FOX LTD</BusinessNameLine1Txt>
      </PreparerFirmName>
      <PreparerUSAddress>
        <AddressLine1Txt>ONE PARKVIEW PLAZA SUITE 710</AddressLine1Txt>
        <CityNm>OAKBROOK TERRACE</CityNm>
        <StateAbbreviationCd>IL</StateAbbreviationCd>
        <ZIPCd>60181</ZIPCd>
      </PreparerUSAddress>
    </PreparerFirmGrp>
    <ReturnTypeCd>990EZ</ReturnTypeCd>
    <TaxPeriodBeginDt>2024-07-01</TaxPeriodBeginDt>
    <Filer>
      <EIN>912119632</EIN>
      <BusinessName>
        <BusinessNameLine1Txt>SOCIETY OF TRIBOLOGISTS AND LUBRICATION</BusinessNameLine1Txt>
        <BusinessNameLine2Txt>ENGINEERS CHICAGO SECTION</BusinessNameLine2Txt>
      </BusinessName>
      <BusinessNameControlTxt>SOCI</BusinessNameControlTxt>
      <PhoneNum>8478255536</PhoneNum>
      <USAddress>
        <AddressLine1Txt>840 BUSSE HIGHWAY</AddressLine1Txt>
        <CityNm>PARK RIDGE</CityNm>
        <StateAbbreviationCd>IL</StateAbbreviationCd>
        <ZIPCd>60068</ZIPCd>
      </USAddress>
    </Filer>
    <BusinessOfficerGrp>
      <PersonNm>REBECCA LINTOW</PersonNm>
      <PersonTitleTxt>EXECUTIVE DIRECTOR</PersonTitleTxt>
      <PhoneNum>8478255536</PhoneNum>
      <SignatureDt>2026-02-03</SignatureDt>
      <DiscussWithPaidPreparerInd>1</DiscussWithPaidPreparerInd>
    </BusinessOfficerGrp>
    <IRSResponsiblePrtyInfoCurrInd>0</IRSResponsiblePrtyInfoCurrInd>
    <PreparerPersonGrp>
      <PreparerPersonNm>PAUL J ROZEK</PreparerPersonNm>
      <PTIN>P00542258</PTIN>
      <PhoneNum>6309541400</PhoneNum>
    </PreparerPersonGrp>
    <TaxYr>2024</TaxYr>
    <BuildTS>2025-03-06 01:10:19Z</BuildTS>
  </ReturnHeader>
  <ReturnData documentCnt="4">
    <IRS990EZ documentId="RetDoc1234200001" referenceDocumentId="RetDoc1051800001 RetDoc2278000001">
      <GroupExemptionNum>3722</GroupExemptionNum>
      <MethodOfAccountingAccrualInd>X</MethodOfAccountingAccrualInd>
      <ScheduleBNotRequiredInd>X</ScheduleBNotRequiredInd>
      <WebsiteAddressTxt>N/A</WebsiteAddressTxt>
      <Organization501c3Ind referenceDocumentId="RetDoc1039100001">X</Organization501c3Ind>
      <TypeOfOrganizationAssocInd>X</TypeOfOrganizationAssocInd>
      <GrossReceiptsAmt>75312</GrossReceiptsAmt>
      <InfoInScheduleOPartIInd>X</InfoInScheduleOPartIInd>
      <ContributionsGiftsGrantsEtcAmt>44256</ContributionsGiftsGrantsEtcAmt>
      <ProgramServiceRevenueAmt>18952</ProgramServiceRevenueAmt>
      <FundraisingGrossIncomeAmt>8683</FundraisingGrossIncomeAmt>
      <SpecialEventsDirectExpensesAmt>9435</SpecialEventsDirectExpensesAmt>
      <SpecialEventsNetIncomeLossAmt>-752</SpecialEventsNetIncomeLossAmt>
      <OtherRevenueTotalAmt>3421</OtherRevenueTotalAmt>
      <TotalRevenueAmt>65877</TotalRevenueAmt>
      <GrantsAndSimilarAmountsPaidAmt>1500</GrantsAndSimilarAmountsPaidAmt>
      <PrintingPublicationsPostageAmt>23114</PrintingPublicationsPostageAmt>
      <OtherExpensesTotalAmt>29744</OtherExpensesTotalAmt>
      <TotalExpensesAmt>54358</TotalExpensesAmt>
      <ExcessOrDeficitForYearAmt>11519</ExcessOrDeficitForYearAmt>
      <NetAssetsOrFundBalancesBOYAmt>86304</NetAssetsOrFundBalancesBOYAmt>
      <OtherChangesInNetAssetsAmt>0</OtherChangesInNetAssetsAmt>
      <NetAssetsOrFundBalancesEOYAmt>97823</NetAssetsOrFundBalancesEOYAmt>
      <CashSavingsAndInvestmentsGrp>
        <BOYAmt>86304</BOYAmt>
        <EOYAmt>97823</EOYAmt>
      </CashSavingsAndInvestmentsGrp>
      <Form990TotalAssetsGrp>
        <BOYAmt>86304</BOYAmt>
        <EOYAmt>97823</EOYAmt>
      </Form990TotalAssetsGrp>
      <SumOfTotalLiabilitiesGrp>
        <BOYAmt>0</BOYAmt>
        <EOYAmt>0</EOYAmt>
      </SumOfTotalLiabilitiesGrp>
      <NetAssetsOrFundBalancesGrp>
        <BOYAmt>86304</BOYAmt>
        <EOYAmt>97823</EOYAmt>
      </NetAssetsOrFundBalancesGrp>
      <InfoInScheduleOPartIIIInd>X</InfoInScheduleOPartIIIInd>
      <PrimaryExemptPurposeTxt>TO ADVANCE THE SCIENCE OF TRIBOLOGY AND THE PRACTICE OF LUBRICATION ENGINEERING IN ORDER TO FOSTER INNOVATION, IMPROVE THE PERFORMANCE OF EQUIPMENT AND PRODUCTS, CONSERVE RESOURCES AND PROTECT THE ENVIRONMENT.</PrimaryExemptPurposeTxt>
      <ProgramSrvcAccomplishmentGrp>
        <DescriptionProgramSrvcAccomTxt>THE CHICAGO SECTION PROVIDES EDUCATION TO MEMBERS AND NON-MEMBERS IN THE FIELD OF LUBRICATION ENGINEERING THROUGH MONTHLY AND QUARTERLY PERIODICALS, RESEARCH PUBLICATIONS, CONFERENCES AND SCHOLARSHIPS.</DescriptionProgramSrvcAccomTxt>
        <GrantsAndAllocationsAmt>1500</GrantsAndAllocationsAmt>
        <ProgramServiceExpensesAmt>48672</ProgramServiceExpensesAmt>
      </ProgramSrvcAccomplishmentGrp>
      <TotalProgramServiceExpensesAmt>48672</TotalProgramServiceExpensesAmt>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>MARY CUTTILL-NIELSEN</PersonNm>
        <TitleTxt>CHAIR</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>2.00</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>0</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>CLAYTON S COOPER</PersonNm>
        <TitleTxt>PAST CHAIR</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>2.00</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>0</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>NICOLE CLARKSON</PersonNm>
        <TitleTxt>VICE CHAIR</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>2.00</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>0</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>ANDREW SCHIFFER</PersonNm>
        <TitleTxt>SECRETARY/TREASURER</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>2.00</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>0</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>PATRICK EUGENE BRUTTO</PersonNm>
        <TitleTxt>COMMITTEE MEMBER</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>2.00</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>0</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>KAREN MAUREEN HARRINGTON</PersonNm>
        <TitleTxt>COMMITTEE MEMBER</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>2.00</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>0</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>JUSTIN KAVANAGH</PersonNm>
        <TitleTxt>COMMITTEE MEMBER</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>2.00</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>0</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>ERIN KERR</PersonNm>
        <TitleTxt>COMMITTEE MEMBER</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>2.00</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>0</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>ALEXES MORGAN</PersonNm>
        <TitleTxt>COMMITTEE MEMBER</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>2.00</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>0</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>KEN PELCZARSKI</PersonNm>
        <TitleTxt>COMMITTEE MEMBER</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>2.00</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>0</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>KEVIN A SAUNDERSON</PersonNm>
        <TitleTxt>COMMITTEE MEMBER</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>2.00</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>0</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <InfoInScheduleOPartVInd>X</InfoInScheduleOPartVInd>
      <ActivitiesNotPreviouslyRptInd>0</ActivitiesNotPreviouslyRptInd>
      <ChgMadeToOrgnzngDocNotRptInd>0</ChgMadeToOrgnzngDocNotRptInd>
      <OrganizationHadUBIInd>0</OrganizationHadUBIInd>
      <SubjectToProxyTaxInd>0</SubjectToProxyTaxInd>
      <OrganizationDissolvedEtcInd>0</OrganizationDissolvedEtcInd>
      <DirectIndirectPltclExpendAmt>0</DirectIndirectPltclExpendAmt>
      <MadeLoansToFromOfficersInd>0</MadeLoansToFromOfficersInd>
      <TaxImposedUnderIRC4911Amt>0</TaxImposedUnderIRC4911Amt>
      <TaxImposedUnderIRC4912Amt>0</TaxImposedUnderIRC4912Amt>
      <TaxImposedUnderIRC4955Amt>0</TaxImposedUnderIRC4955Amt>
      <EngagedInExcessBenefitTransInd>0</EngagedInExcessBenefitTransInd>
      <TaxImposedOnOrganizationMgrAmt>0</TaxImposedOnOrganizationMgrAmt>
      <TaxReimbursedByOrganizationAmt>0</TaxReimbursedByOrganizationAmt>
      <ProhibitedTaxShelterTransInd>0</ProhibitedTaxShelterTransInd>
      <StatesWhereCopyOfReturnIsFldCd>IL</StatesWhereCopyOfReturnIsFldCd>
      <BooksInCareOfDetail>
        <BusinessName>
          <BusinessNameLine1Txt>REBECCA LINTOW</BusinessNameLine1Txt>
        </BusinessName>
        <USAddress>
          <AddressLine1Txt>840 BUSSE HIGHWAY</AddressLine1Txt>
          <CityNm>PARK RIDGE</CityNm>
          <StateAbbreviationCd>IL</StateAbbreviationCd>
          <ZIPCd>60068</ZIPCd>
        </USAddress>
        <PhoneNum>8478255536</PhoneNum>
      </BooksInCareOfDetail>
      <ForeignFinancialAccountInd>0</ForeignFinancialAccountInd>
      <ForeignOfficeInd>0</ForeignOfficeInd>
      <DonorAdvisedFndsInd>0</DonorAdvisedFndsInd>
      <OperateHospitalInd>0</OperateHospitalInd>
      <TanningServicesProvidedInd>0</TanningServicesProvidedInd>
      <RelatedOrganizationCtrlEntInd>0</RelatedOrganizationCtrlEntInd>
      <PoliticalCampaignActyInd>0</PoliticalCampaignActyInd>
      <LobbyingActivitiesInd>0</LobbyingActivitiesInd>
      <SchoolOperatingInd>0</SchoolOperatingInd>
      <TrnsfrExmptNonChrtblRltdOrgInd>0</TrnsfrExmptNonChrtblRltdOrgInd>
      <PartVIOfCompOfHghstPdEmplTxt>NONE</PartVIOfCompOfHghstPdEmplTxt>
      <PartVIHghstPdCntrctProfSrvcTxt>NONE</PartVIHghstPdCntrctProfSrvcTxt>
      <FiledScheduleAInd>1</FiledScheduleAInd>
    </IRS990EZ>
    <IRS990ScheduleA documentId="RetDoc1039100001">
      <PubliclySupportedOrg509a2Ind>X</PubliclySupportedOrg509a2Ind>
      <GiftsGrantsContrisRcvd509Grp>
        <CurrentTaxYearMinus4YearsAmt>32796</CurrentTaxYearMinus4YearsAmt>
        <CurrentTaxYearMinus3YearsAmt>36497</CurrentTaxYearMinus3YearsAmt>
        <CurrentTaxYearMinus2YearsAmt>26557</CurrentTaxYearMinus2YearsAmt>
        <CurrentTaxYearMinus1YearAmt>34573</CurrentTaxYearMinus1YearAmt>
        <CurrentTaxYearAmt>44256</CurrentTaxYearAmt>
        <TotalAmt>174679</TotalAmt>
      </GiftsGrantsContrisRcvd509Grp>
      <GrossReceiptsAdmissionsGrp>
        <CurrentTaxYearMinus4YearsAmt>14341</CurrentTaxYearMinus4YearsAmt>
        <CurrentTaxYearMinus3YearsAmt>26414</CurrentTaxYearMinus3YearsAmt>
        <CurrentTaxYearMinus2YearsAmt>48907</CurrentTaxYearMinus2YearsAmt>
        <CurrentTaxYearMinus1YearAmt>40543</CurrentTaxYearMinus1YearAmt>
        <CurrentTaxYearAmt>27635</CurrentTaxYearAmt>
        <TotalAmt>157840</TotalAmt>
      </GrossReceiptsAdmissionsGrp>
      <Total509Grp>
        <CurrentTaxYearMinus4YearsAmt>47137</CurrentTaxYearMinus4YearsAmt>
        <CurrentTaxYearMinus3YearsAmt>62911</CurrentTaxYearMinus3YearsAmt>
        <CurrentTaxYearMinus2YearsAmt>75464</CurrentTaxYearMinus2YearsAmt>
        <CurrentTaxYearMinus1YearAmt>75116</CurrentTaxYearMinus1YearAmt>
        <CurrentTaxYearAmt>71891</CurrentTaxYearAmt>
        <TotalAmt>332519</TotalAmt>
      </Total509Grp>
      <AmountsRcvdDsqlfyPersonGrp>
        <TotalAmt>0</TotalAmt>
      </AmountsRcvdDsqlfyPersonGrp>
      <SubstantialContributorsAmtGrp>
        <TotalAmt>0</TotalAmt>
      </SubstantialContributorsAmtGrp>
      <SubstAndDsqlfyPrsnsTotGrp>
        <TotalAmt>0</TotalAmt>
      </SubstAndDsqlfyPrsnsTotGrp>
      <PublicSupportTotal509Amt>332519</PublicSupportTotal509Amt>
      <GrossInvestmentIncome509Grp>
        <CurrentTaxYearMinus1YearAmt>3130</CurrentTaxYearMinus1YearAmt>
        <CurrentTaxYearAmt>3421</CurrentTaxYearAmt>
        <TotalAmt>6551</TotalAmt>
      </GrossInvestmentIncome509Grp>
      <InvestmentIncomeAndUBTIGrp>
        <CurrentTaxYearMinus1YearAmt>3130</CurrentTaxYearMinus1YearAmt>
        <CurrentTaxYearAmt>3421</CurrentTaxYearAmt>
        <TotalAmt>6551</TotalAmt>
      </InvestmentIncomeAndUBTIGrp>
      <TotalSupportCalendarYearGrp>
        <CurrentTaxYearMinus4YearsAmt>47137</CurrentTaxYearMinus4YearsAmt>
        <CurrentTaxYearMinus3YearsAmt>62911</CurrentTaxYearMinus3YearsAmt>
        <CurrentTaxYearMinus2YearsAmt>75464</CurrentTaxYearMinus2YearsAmt>
        <CurrentTaxYearMinus1YearAmt>78246</CurrentTaxYearMinus1YearAmt>
        <CurrentTaxYearAmt>75312</CurrentTaxYearAmt>
        <TotalAmt>339070</TotalAmt>
      </TotalSupportCalendarYearGrp>
      <PublicSupportCY509Pct>0.98070</PublicSupportCY509Pct>
      <PublicSupportPY509Pct>0.99710</PublicSupportPY509Pct>
      <InvestmentIncomeCYPct>0.01930</InvestmentIncomeCYPct>
      <InvestmentIncomePYPct>0.00290</InvestmentIncomePYPct>
      <ThirtyThrPctSuprtTestsCY509Ind>X</ThirtyThrPctSuprtTestsCY509Ind>
    </IRS990ScheduleA>
    <IRS990ScheduleO documentId="RetDoc1051800001">
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990-EZ, PART I, LINE 8 - OTHER REVENUE</FormAndLineReferenceDesc>
        <ExplanationTxt>DESCRIPTION: INTEREST. AMOUNT: 3,421.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990-EZ, PART I, LINE 10 - GRANTS AND SIMILAR AMOUNTS PAID</FormAndLineReferenceDesc>
        <ExplanationTxt>ACTIVITY CLASSIFICATION: CNC MACHINIST SCHOLARSHIP. GRANTEE NAME: PABLO ESCOBEDO. DATE OF GIFT: 04/14/25. AMOUNT GIVEN: 750.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990-EZ, PART I, LINE 10 - GRANTS AND SIMILAR AMOUNTS PAID</FormAndLineReferenceDesc>
        <ExplanationTxt>ACTIVITY CLASSIFICATION: CNC MACHINIST SCHOLARSHIP. GRANTEE NAME: MATHEW SMID. DATE OF GIFT: 04/14/25. AMOUNT GIVEN: 750. TOTAL INCLUDED ON FORM 990-EZ, LINE 10: 1,500.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990-EZ, PART I, LINE 16 - OTHER EXPENSES</FormAndLineReferenceDesc>
        <ExplanationTxt>DESCRIPTION: EDUCATION COURSES. AMOUNT: 2,603. DESCRIPTION: MEETING. AMOUNT: 21,128. DESCRIPTION: SECTION ADMINISTRATION. AMOUNT: 5,685. DESCRIPTION: OUTREACH. AMOUNT: 172. DESCRIPTION: OTHER. AMOUNT: 156. TOTAL TO FORM 990-EZ, LINE 16: 29,744.</ExplanationTxt>
      </SupplementalInformationDetail>
    </IRS990ScheduleO>
    <TransferPrsnlBnftContractsDecl documentId="RetDoc2278000001">
      <DeclarationDesc>THE ORGANIZATION DID NOT, DURING THE YEAR, RECEIVE ANY FUNDS, DIRECTLY,OR INDIRECTLY, TO PAY PREMIUMS ON A PERSONAL BENEFIT CONTRACT.THE ORGANIZATION, DID NOT, DURING THE YEAR, PAY ANY PREMIUMS, DIRECTLY,OR INDIRECTLY, ON A PERSONAL BENEFIT CONTRACT.</DeclarationDesc>
    </TransferPrsnlBnftContractsDecl>
  </ReturnData>
</Return>