﻿<?xml version="1.0" encoding="utf-8"?>
<Return xmlns="http://www.irs.gov/efile" xsi:schemaLocation="http://www.irs.gov/efile" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" returnVersion="2023v6.0">
  <ReturnHeader binaryAttachmentCnt="0">
    <ReturnTs>2025-03-18T09:56:54-05:00</ReturnTs>
    <TaxPeriodEndDt>2024-05-31</TaxPeriodEndDt>
    <PreparerFirmGrp>
      <PreparerFirmName>
        <BusinessNameLine1Txt>DOWNEY ADVISORS LLC</BusinessNameLine1Txt>
      </PreparerFirmName>
      <PreparerUSAddress>
        <AddressLine1Txt>2205 COTTONWOOD DR</AddressLine1Txt>
        <CityNm>GLENVIEW</CityNm>
        <StateAbbreviationCd>IL</StateAbbreviationCd>
        <ZIPCd>60026</ZIPCd>
      </PreparerUSAddress>
    </PreparerFirmGrp>
    <ReturnTypeCd>990EZ</ReturnTypeCd>
    <TaxPeriodBeginDt>2023-06-01</TaxPeriodBeginDt>
    <Filer>
      <EIN>237385862</EIN>
      <BusinessName>
        <BusinessNameLine1Txt>GLENBROOK SOUTH INSTRUMENTAL LEAGUE</BusinessNameLine1Txt>
      </BusinessName>
      <InCareOfNm>% AMY DOWNEY</InCareOfNm>
      <BusinessNameControlTxt>GLEN</BusinessNameControlTxt>
      <PhoneNum>8472123505</PhoneNum>
      <USAddress>
        <AddressLine1Txt>4000 WEST LAKE AVENUE</AddressLine1Txt>
        <CityNm>GLENVIEW</CityNm>
        <StateAbbreviationCd>IL</StateAbbreviationCd>
        <ZIPCd>60026</ZIPCd>
      </USAddress>
    </Filer>
    <BusinessOfficerGrp>
      <PersonNm>AMY DOWNEY</PersonNm>
      <PersonTitleTxt>TREASURER</PersonTitleTxt>
      <PhoneNum>8472123505</PhoneNum>
      <SignatureDt>2024-07-25</SignatureDt>
    </BusinessOfficerGrp>
    <IRSResponsiblePrtyInfoCurrInd>true</IRSResponsiblePrtyInfoCurrInd>
    <PreparerPersonGrp>
      <PreparerPersonNm>AMY DOWNEY OWNER</PreparerPersonNm>
      <PTIN>P00446932</PTIN>
      <PhoneNum>8472123505</PhoneNum>
    </PreparerPersonGrp>
    <TaxYr>2023</TaxYr>
    <BuildTS>2025-03-06 01:10:19Z</BuildTS>
  </ReturnHeader>
  <ReturnData documentCnt="4">
    <IRS990EZ documentId="IRS990EZ" referenceDocumentId="IRS990ScheduleO">
      <MethodOfAccountingCashInd>X</MethodOfAccountingCashInd>
      <WebsiteAddressTxt>WWW.GBSIL.ORG</WebsiteAddressTxt>
      <Organization501c3Ind referenceDocumentId="IRS990ScheduleA">X</Organization501c3Ind>
      <TypeOfOrganizationCorpInd>X</TypeOfOrganizationCorpInd>
      <GrossReceiptsAmt>50381</GrossReceiptsAmt>
      <InfoInScheduleOPartIInd>X</InfoInScheduleOPartIInd>
      <ContributionsGiftsGrantsEtcAmt>10000</ContributionsGiftsGrantsEtcAmt>
      <ProgramServiceRevenueAmt>33890</ProgramServiceRevenueAmt>
      <CostOrOtherBasisExpenseSaleAmt>0</CostOrOtherBasisExpenseSaleAmt>
      <GainOrLossFromSaleOfAssetsAmt>0</GainOrLossFromSaleOfAssetsAmt>
      <FundraisingGrossIncomeAmt>6491</FundraisingGrossIncomeAmt>
      <SpecialEventsDirectExpensesAmt>0</SpecialEventsDirectExpensesAmt>
      <SpecialEventsNetIncomeLossAmt>6491</SpecialEventsNetIncomeLossAmt>
      <CostOfGoodsSoldAmt>0</CostOfGoodsSoldAmt>
      <GrossProfitLossSlsOfInvntryAmt>0</GrossProfitLossSlsOfInvntryAmt>
      <TotalRevenueAmt>50381</TotalRevenueAmt>
      <SalariesOtherCompEmplBnftAmt>0</SalariesOtherCompEmplBnftAmt>
      <OtherExpensesTotalAmt>59456</OtherExpensesTotalAmt>
      <TotalExpensesAmt>59456</TotalExpensesAmt>
      <ExcessOrDeficitForYearAmt>-9075</ExcessOrDeficitForYearAmt>
      <NetAssetsOrFundBalancesBOYAmt>44903</NetAssetsOrFundBalancesBOYAmt>
      <NetAssetsOrFundBalancesEOYAmt>35828</NetAssetsOrFundBalancesEOYAmt>
      <InfoInScheduleOPartIIInd>X</InfoInScheduleOPartIIInd>
      <CashSavingsAndInvestmentsGrp>
        <BOYAmt>44903</BOYAmt>
        <EOYAmt>35828</EOYAmt>
      </CashSavingsAndInvestmentsGrp>
      <LandAndBuildingsGrp>
        <BOYAmt>0</BOYAmt>
        <EOYAmt>0</EOYAmt>
      </LandAndBuildingsGrp>
      <OtherAssetsTotalDetail>
        <BOYAmt>2010</BOYAmt>
        <EOYAmt>113</EOYAmt>
      </OtherAssetsTotalDetail>
      <Form990TotalAssetsGrp>
        <BOYAmt>46913</BOYAmt>
        <EOYAmt>35941</EOYAmt>
      </Form990TotalAssetsGrp>
      <SumOfTotalLiabilitiesGrp>
        <BOYAmt>2010</BOYAmt>
        <EOYAmt>113</EOYAmt>
      </SumOfTotalLiabilitiesGrp>
      <NetAssetsOrFundBalancesGrp>
        <BOYAmt>44903</BOYAmt>
        <EOYAmt>35828</EOYAmt>
      </NetAssetsOrFundBalancesGrp>
      <PrimaryExemptPurposeTxt>SUPPORT OF THE MUSIC PROGRAM WHICH PROVIDES EXPERIENCES FOR HIGH SCHOOL STUDENTS IN SEVERAL ASPECTS OF MUSIC - JAZZ, MARCHING AND CONCERT.</PrimaryExemptPurposeTxt>
      <ProgramSrvcAccomplishmentGrp>
        <DescriptionProgramSrvcAccomTxt>SUPPORT OF THE MUSIC PROGRAM, WHICH PROVIDES EXPERIENCES FOR HIGH SCHOOL STUDENTS IN SEVERAL ASPECTS OF MUSIC - JAZZ, MARCHING ADN CONCERT.</DescriptionProgramSrvcAccomTxt>
        <ProgramServiceExpensesAmt>39910</ProgramServiceExpensesAmt>
      </ProgramSrvcAccomplishmentGrp>
      <TotalProgramServiceExpensesAmt>39910</TotalProgramServiceExpensesAmt>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>BETH PARKER</PersonNm>
        <TitleTxt>PRESIDENT</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>10.0</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>0</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>AMY DOWNEY</PersonNm>
        <TitleTxt>TREASURER</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>10.0</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>0</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>RHONDA HUEBLEIN</PersonNm>
        <TitleTxt>SECRETARY</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>10.0</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>0</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <ActivitiesNotPreviouslyRptInd>false</ActivitiesNotPreviouslyRptInd>
      <ChgMadeToOrgnzngDocNotRptInd>false</ChgMadeToOrgnzngDocNotRptInd>
      <OrganizationHadUBIInd>false</OrganizationHadUBIInd>
      <SubjectToProxyTaxInd>false</SubjectToProxyTaxInd>
      <OrganizationDissolvedEtcInd>false</OrganizationDissolvedEtcInd>
      <Form1120PolFiledInd>false</Form1120PolFiledInd>
      <MadeLoansToFromOfficersInd>false</MadeLoansToFromOfficersInd>
      <EngagedInExcessBenefitTransInd>false</EngagedInExcessBenefitTransInd>
      <ProhibitedTaxShelterTransInd>false</ProhibitedTaxShelterTransInd>
      <BooksInCareOfDetail>
        <PersonNm>AMY DOWNEY</PersonNm>
        <USAddress>
          <AddressLine1Txt>2205 COTTONWOOD DR</AddressLine1Txt>
          <CityNm>GLENVIEW</CityNm>
          <StateAbbreviationCd>IL</StateAbbreviationCd>
          <ZIPCd>60026</ZIPCd>
        </USAddress>
        <PhoneNum>8472123505</PhoneNum>
      </BooksInCareOfDetail>
      <ForeignFinancialAccountInd>false</ForeignFinancialAccountInd>
      <ForeignOfficeInd>false</ForeignOfficeInd>
      <DonorAdvisedFndsInd>false</DonorAdvisedFndsInd>
      <OperateHospitalInd>false</OperateHospitalInd>
      <TanningServicesProvidedInd>false</TanningServicesProvidedInd>
      <RelatedOrganizationCtrlEntInd>false</RelatedOrganizationCtrlEntInd>
      <TransactionWithControlEntInd>false</TransactionWithControlEntInd>
      <PoliticalCampaignActyInd>false</PoliticalCampaignActyInd>
      <LobbyingActivitiesInd>false</LobbyingActivitiesInd>
      <TrnsfrExmptNonChrtblRltdOrgInd>false</TrnsfrExmptNonChrtblRltdOrgInd>
      <FiledScheduleAInd>true</FiledScheduleAInd>
    </IRS990EZ>
    <IRS990ScheduleA documentId="IRS990ScheduleA">
      <PubliclySupportedOrg509a2Ind>X</PubliclySupportedOrg509a2Ind>
      <GiftsGrantsContrisRcvd509Grp>
        <CurrentTaxYearMinus4YearsAmt>1219</CurrentTaxYearMinus4YearsAmt>
        <CurrentTaxYearMinus3YearsAmt>3000</CurrentTaxYearMinus3YearsAmt>
        <CurrentTaxYearMinus2YearsAmt>1015</CurrentTaxYearMinus2YearsAmt>
        <CurrentTaxYearMinus1YearAmt>4090</CurrentTaxYearMinus1YearAmt>
        <CurrentTaxYearAmt>16491</CurrentTaxYearAmt>
        <TotalAmt>25815</TotalAmt>
      </GiftsGrantsContrisRcvd509Grp>
      <GrossReceiptsAdmissionsGrp>
        <CurrentTaxYearMinus4YearsAmt>82976</CurrentTaxYearMinus4YearsAmt>
        <CurrentTaxYearMinus3YearsAmt>2778</CurrentTaxYearMinus3YearsAmt>
        <CurrentTaxYearMinus2YearsAmt>34542</CurrentTaxYearMinus2YearsAmt>
        <CurrentTaxYearMinus1YearAmt>43148</CurrentTaxYearMinus1YearAmt>
        <CurrentTaxYearAmt>34045</CurrentTaxYearAmt>
        <TotalAmt>197489</TotalAmt>
      </GrossReceiptsAdmissionsGrp>
      <GrossReceiptsNonUnrltBusGrp>
        <TotalAmt>0</TotalAmt>
      </GrossReceiptsNonUnrltBusGrp>
      <TaxRevLeviedOrgnztnlBnft509Grp>
        <TotalAmt>0</TotalAmt>
      </TaxRevLeviedOrgnztnlBnft509Grp>
      <GovtFurnSrvcFcltsVl509Grp>
        <TotalAmt>0</TotalAmt>
      </GovtFurnSrvcFcltsVl509Grp>
      <Total509Grp>
        <CurrentTaxYearMinus4YearsAmt>84195</CurrentTaxYearMinus4YearsAmt>
        <CurrentTaxYearMinus3YearsAmt>5778</CurrentTaxYearMinus3YearsAmt>
        <CurrentTaxYearMinus2YearsAmt>35557</CurrentTaxYearMinus2YearsAmt>
        <CurrentTaxYearMinus1YearAmt>47238</CurrentTaxYearMinus1YearAmt>
        <CurrentTaxYearAmt>50536</CurrentTaxYearAmt>
        <TotalAmt>223304</TotalAmt>
      </Total509Grp>
      <AmountsRcvdDsqlfyPersonGrp>
        <TotalAmt>0</TotalAmt>
      </AmountsRcvdDsqlfyPersonGrp>
      <SubstantialContributorsAmtGrp>
        <TotalAmt>0</TotalAmt>
      </SubstantialContributorsAmtGrp>
      <SubstAndDsqlfyPrsnsTotGrp>
        <TotalAmt>0</TotalAmt>
      </SubstAndDsqlfyPrsnsTotGrp>
      <PublicSupportTotal509Amt>223304</PublicSupportTotal509Amt>
      <GrossInvestmentIncome509Grp>
        <TotalAmt>0</TotalAmt>
      </GrossInvestmentIncome509Grp>
      <Post1975UBTIGrp>
        <TotalAmt>0</TotalAmt>
      </Post1975UBTIGrp>
      <InvestmentIncomeAndUBTIGrp>
        <TotalAmt>0</TotalAmt>
      </InvestmentIncomeAndUBTIGrp>
      <NetIncomeFromOtherUBIGrp>
        <TotalAmt>0</TotalAmt>
      </NetIncomeFromOtherUBIGrp>
      <OtherIncome509Grp>
        <TotalAmt>0</TotalAmt>
      </OtherIncome509Grp>
      <TotalSupportCalendarYearGrp>
        <CurrentTaxYearMinus4YearsAmt>84195</CurrentTaxYearMinus4YearsAmt>
        <CurrentTaxYearMinus3YearsAmt>5778</CurrentTaxYearMinus3YearsAmt>
        <CurrentTaxYearMinus2YearsAmt>35557</CurrentTaxYearMinus2YearsAmt>
        <CurrentTaxYearMinus1YearAmt>47238</CurrentTaxYearMinus1YearAmt>
        <CurrentTaxYearAmt>50536</CurrentTaxYearAmt>
        <TotalAmt>223304</TotalAmt>
      </TotalSupportCalendarYearGrp>
      <PublicSupportCY509Pct>1.00000</PublicSupportCY509Pct>
      <PublicSupportPY509Pct>1.00000</PublicSupportPY509Pct>
      <InvestmentIncomeCYPct>0.00000</InvestmentIncomeCYPct>
      <InvestmentIncomePYPct>0.00000</InvestmentIncomePYPct>
      <ThirtyThrPctSuprtTestsCY509Ind>X</ThirtyThrPctSuprtTestsCY509Ind>
    </IRS990ScheduleA>
    <IRS990ScheduleB documentId="IRS990ScheduleB">
      <ContributorInformationGrp>
        <ContributorNum>RESTRICTED</ContributorNum>
        <ContributorBusinessName>
          <BusinessNameLine1>RESTRICTED</BusinessNameLine1>
        </ContributorBusinessName>
        <ContributorUSAddress>
          <AddressLine1>RESTRICTED</AddressLine1>
          <AddressLine2>RESTRICTED</AddressLine2>
          <City>RESTRICTED</City>
          <State>RESTRICTED</State>
          <ZIPCode>RESTRICTED</ZIPCode>
        </ContributorUSAddress>
        <TotalContributionsAmt>RESTRICTED</TotalContributionsAmt>
      </ContributorInformationGrp>
    </IRS990ScheduleB>
    <IRS990ScheduleO documentId="IRS990ScheduleO">
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990EZ PART I LINE 16</FormAndLineReferenceDesc>
        <ExplanationTxt>Description:OFFICE Amount:593</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990EZ PART I LINE 16</FormAndLineReferenceDesc>
        <ExplanationTxt>Description:UNIFORM COSTS Amount:5271</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990EZ PART I LINE 16</FormAndLineReferenceDesc>
        <ExplanationTxt>Description:BAND CAMP/MEALS Amount:5918</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990EZ PART I LINE 16</FormAndLineReferenceDesc>
        <ExplanationTxt>Description:STUDENT AWARDS/SCHOLARSHIPS Amount:2088</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990EZ PART I LINE 16</FormAndLineReferenceDesc>
        <ExplanationTxt>Description:MARCHING BAND PROGRAM COSTS Amount:39910</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990EZ PART I LINE 16</FormAndLineReferenceDesc>
        <ExplanationTxt>Description:RECRUITING Amount:442</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990EZ PART I LINE 16</FormAndLineReferenceDesc>
        <ExplanationTxt>Description:DRUM MAJOR CLINIC Amount:1785</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990EZ PART I LINE 16</FormAndLineReferenceDesc>
        <ExplanationTxt>Description:FUNDRAISING EVENTS Amount:1761</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990EZ PART I LINE 16</FormAndLineReferenceDesc>
        <ExplanationTxt>Description:TRANSFER STUDENT FUNDS TO GBS Amount:1688</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990EZ PART II LINE 24</FormAndLineReferenceDesc>
        <ExplanationTxt>Description:STUDENT FUNDRAISING ACCOUNTS BOY Amount:2010 EOY Amount:113</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990EZ PART II LINE 26</FormAndLineReferenceDesc>
        <ExplanationTxt>Description:STUDENT FUNDRAISING ACCOUNTS BOY Amount:2010 EOY Amount:113</ExplanationTxt>
      </SupplementalInformationDetail>
    </IRS990ScheduleO>
  </ReturnData>
</Return>