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      <TotalCompGT150K>1</TotalCompGT150K>
      <CompensationFromOtherSources>0</CompensationFromOtherSources>
      <ContractorCompensation>
        <NameOfContractor>
          <NameBusiness>
            <BusinessNameLine1>MASSACHUSETTS CONVENTION CENTER AUTHORIT</BusinessNameLine1>
          </NameBusiness>
        </NameOfContractor>
        <AddressOfContractor>
          <AddressUS>
            <AddressLine1>415 SUMMER STREET</AddressLine1>
            <City>BOSTON</City>
            <State>MA</State>
            <ZIPCode>02210</ZIPCode>
          </AddressUS>
        </AddressOfContractor>
        <DescriptionOfServices>EVENT SPACE RENTAL</DescriptionOfServices>
        <Compensation>489749</Compensation>
      </ContractorCompensation>
      <ContractorCompensation>
        <NameOfContractor>
          <NameBusiness>
            <BusinessNameLine1>LEVY PREMIUM FOOD SERVICE</BusinessNameLine1>
          </NameBusiness>
        </NameOfContractor>
        <AddressOfContractor>
          <AddressUS>
            <AddressLine1>980 N MICHIGAN AVENUE</AddressLine1>
            <City>CHICAGO</City>
            <State>IL</State>
            <ZIPCode>60611</ZIPCode>
          </AddressUS>
        </AddressOfContractor>
        <DescriptionOfServices>CATERING</DescriptionOfServices>
        <Compensation>317776</Compensation>
      </ContractorCompensation>
      <ContractorCompensation>
        <NameOfContractor>
          <NameBusiness>
            <BusinessNameLine1>PRINT RESOURCES INC</BusinessNameLine1>
          </NameBusiness>
        </NameOfContractor>
        <AddressOfContractor>
          <AddressUS>
            <AddressLine1>2720 19TH STREET</AddressLine1>
            <City>BIRMINGHAM</City>
            <State>AL</State>
            <ZIPCode>35209</ZIPCode>
          </AddressUS>
        </AddressOfContractor>
        <DescriptionOfServices>PRINTING</DescriptionOfServices>
        <Compensation>229138</Compensation>
      </ContractorCompensation>
      <ContractorCompensation>
        <NameOfContractor>
          <NameBusiness>
            <BusinessNameLine1>RHODE PLANNING &amp; MANAGEMENT SERVICES IN</BusinessNameLine1>
          </NameBusiness>
        </NameOfContractor>
        <AddressOfContractor>
          <AddressUS>
            <AddressLine1>640 TEN ROAD</AddressLine1>
            <City>NORTH KINGSTOWN</City>
            <State>RI</State>
            <ZIPCode>02852</ZIPCode>
          </AddressUS>
        </AddressOfContractor>
        <DescriptionOfServices>TRANSPORTATION</DescriptionOfServices>
        <Compensation>215003</Compensation>
      </ContractorCompensation>
      <ContractorCompensation>
        <NameOfContractor>
          <NameBusiness>
            <BusinessNameLine1>PROJECTION INC</BusinessNameLine1>
          </NameBusiness>
        </NameOfContractor>
        <AddressOfContractor>
          <AddressUS>
            <AddressLine1>415 SUMMER STREET</AddressLine1>
            <City>BOSTON</City>
            <State>MA</State>
            <ZIPCode>02210</ZIPCode>
          </AddressUS>
        </AddressOfContractor>
        <DescriptionOfServices>AUDIO / VISUAL SERVICES</DescriptionOfServices>
        <Compensation>174430</Compensation>
      </ContractorCompensation>
      <NumberOfContractorsGT100K>5</NumberOfContractorsGT100K>
      <AllOtherContributions>32050</AllOtherContributions>
      <TotalContributions>32050</TotalContributions>
      <ProgramServiceRevenue>
        <Description>YANKEE DENTAL CONGRESS</Description>
        <BusinessCode>900099</BusinessCode>
        <TotalRevenueColumn>6622966</TotalRevenueColumn>
        <ExclusionAmount>6622966</ExclusionAmount>
      </ProgramServiceRevenue>
      <ProgramServiceRevenue>
        <Description>MEMBERSHIP DUES</Description>
        <BusinessCode>900099</BusinessCode>
        <TotalRevenueColumn>2071508</TotalRevenueColumn>
        <RelatedOrExemptFunctionIncome>2071508</RelatedOrExemptFunctionIncome>
      </ProgramServiceRevenue>
      <ProgramServiceRevenue>
        <Description>CONFERENCES AND WORKSH</Description>
        <BusinessCode>900099</BusinessCode>
        <TotalRevenueColumn>333128</TotalRevenueColumn>
        <RelatedOrExemptFunctionIncome>333128</RelatedOrExemptFunctionIncome>
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      <ProgramServiceRevenue>
        <Description>CONTINUING EDUCATION</Description>
        <BusinessCode>900099</BusinessCode>
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        <RelatedOrExemptFunctionIncome>311148</RelatedOrExemptFunctionIncome>
      </ProgramServiceRevenue>
      <ProgramServiceRevenue>
        <Description>ADVERTISING</Description>
        <BusinessCode>541800</BusinessCode>
        <TotalRevenueColumn>149312</TotalRevenueColumn>
        <UnrelatedBusinessRevenue>149312</UnrelatedBusinessRevenue>
      </ProgramServiceRevenue>
      <TotalProgramServiceRevenue>9488062</TotalProgramServiceRevenue>
      <InvestmentIncome>
        <TotalRevenueColumn>218690</TotalRevenueColumn>
        <ExclusionAmount>218690</ExclusionAmount>
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      <RoyaltiesRevenue>
        <TotalRevenueColumn>299196</TotalRevenueColumn>
        <ExclusionAmount>299196</ExclusionAmount>
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      <GrossRents>
        <Real>509599</Real>
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      <LessRentalExpenses>
        <Real>582213</Real>
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      <RentalIncomeOrLoss>
        <Real>-72614</Real>
      </RentalIncomeOrLoss>
      <NetRentalIncomeOrLoss>
        <TotalRevenueColumn>-72614</TotalRevenueColumn>
        <UnrelatedBusinessRevenue>-67079</UnrelatedBusinessRevenue>
        <ExclusionAmount>-5535</ExclusionAmount>
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      <GrossAmountSalesAssets>
        <Securities>5530824</Securities>
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      <LessCostOthBasisSalesExpenses>
        <Securities>5377423</Securities>
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      <GainOrLoss>
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      <NetGainOrLossInvestments>
        <TotalRevenueColumn>153401</TotalRevenueColumn>
        <ExclusionAmount>153401</ExclusionAmount>
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      <OtherRevenueMisc>
        <Description>EQUITY IN WHOLLY OWNED</Description>
        <BusinessCode>900099</BusinessCode>
        <TotalRevenueColumn>43134</TotalRevenueColumn>
        <ExclusionAmount>43134</ExclusionAmount>
      </OtherRevenueMisc>
      <OtherRevenueMisc>
        <Description>MANAGEMENT FEE</Description>
        <BusinessCode>900099</BusinessCode>
        <TotalRevenueColumn>10000</TotalRevenueColumn>
        <RelatedOrExemptFunctionIncome>10000</RelatedOrExemptFunctionIncome>
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      <MiscellaneousRevenue>
        <TotalRevenueColumn>125230</TotalRevenueColumn>
        <RelatedOrExemptFunctionIncome>125230</RelatedOrExemptFunctionIncome>
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      <TotalOtherRevenue>178364</TotalOtherRevenue>
      <TotalRevenue>
        <TotalRevenueColumn>10297149</TotalRevenueColumn>
        <RelatedOrExemptFunctionIncome>2851014</RelatedOrExemptFunctionIncome>
        <UnrelatedBusinessRevenue>82233</UnrelatedBusinessRevenue>
        <ExclusionAmount>7331852</ExclusionAmount>
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      <GrantsToDomesticOrgs>
        <Total>77375</Total>
      </GrantsToDomesticOrgs>
      <CompCurrentOfficersDirectors>
        <Total>499342</Total>
      </CompCurrentOfficersDirectors>
      <OtherSalariesAndWages>
        <Total>2229339</Total>
      </OtherSalariesAndWages>
      <PensionPlanContributions>
        <Total>180525</Total>
      </PensionPlanContributions>
      <OtherEmployeeBenefits>
        <Total>210503</Total>
      </OtherEmployeeBenefits>
      <PayrollTaxes>
        <Total>207546</Total>
      </PayrollTaxes>
      <FeesForServicesLegal>
        <Total>230160</Total>
      </FeesForServicesLegal>
      <FeesForServicesAccounting>
        <Total>54265</Total>
      </FeesForServicesAccounting>
      <OfficeExpenses>
        <Total>310810</Total>
      </OfficeExpenses>
      <Occupancy>
        <Total>118484</Total>
      </Occupancy>
      <Travel>
        <Total>38452</Total>
      </Travel>
      <ConferencesMeetings>
        <Total>2852566</Total>
      </ConferencesMeetings>
      <Interest>
        <Total>111643</Total>
      </Interest>
      <DepreciationDepletion>
        <Total>163505</Total>
      </DepreciationDepletion>
      <Insurance>
        <Total>45988</Total>
      </Insurance>
      <OtherExpenses>
        <Description>INITIATIVES</Description>
        <Total>363564</Total>
      </OtherExpenses>
      <OtherExpenses>
        <Description>SEMINARS AND WORKSHOPS</Description>
        <Total>332536</Total>
      </OtherExpenses>
      <OtherExpenses>
        <Description>PUBLIC AWARENESS PROGRA</Description>
        <Total>267680</Total>
      </OtherExpenses>
      <OtherExpenses>
        <Description>BANK FEES</Description>
        <Total>205056</Total>
      </OtherExpenses>
      <OtherExpenses>
        <Description>DELEGATE MEETINGS</Description>
        <Total>158345</Total>
      </OtherExpenses>
      <AllOtherExpenses>
        <Total>875584</Total>
      </AllOtherExpenses>
      <TotalFunctionalExpenses>
        <Total>9533268</Total>
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      <CashNonInterestBearing>
        <BOY>1786865</BOY>
        <EOY>911481</EOY>
      </CashNonInterestBearing>
      <SavingsAndTempCashInvestments>
        <BOY>1197582</BOY>
        <EOY>1742541</EOY>
      </SavingsAndTempCashInvestments>
      <AccountsReceivable>
        <BOY>226198</BOY>
        <EOY>142204</EOY>
      </AccountsReceivable>
      <PrepaidExpensesDeferredCharges>
        <BOY>264926</BOY>
        <EOY>413876</EOY>
      </PrepaidExpensesDeferredCharges>
      <LandBuildingsEquipmentBasis>7601014</LandBuildingsEquipmentBasis>
      <LandBldgEquipmentAccumDeprec>2011263</LandBldgEquipmentAccumDeprec>
      <LandBuildingsEquipmentBasisNet>
        <BOY>5768494</BOY>
        <EOY>5589751</EOY>
      </LandBuildingsEquipmentBasisNet>
      <InvestmentsPubTradedSecurities>
        <BOY>5092953</BOY>
        <EOY>7109626</EOY>
      </InvestmentsPubTradedSecurities>
      <InvestmentsOtherSecurities>
        <BOY>232769</BOY>
        <EOY>277989</EOY>
      </InvestmentsOtherSecurities>
      <OtherAssetsTotal>
        <BOY>0</BOY>
        <EOY>32818</EOY>
      </OtherAssetsTotal>
      <TotalAssets>
        <BOY>14569787</BOY>
        <EOY>16220286</EOY>
      </TotalAssets>
      <AccountsPayableAccruedExpenses>
        <BOY>602478</BOY>
        <EOY>648824</EOY>
      </AccountsPayableAccruedExpenses>
      <DeferredRevenue>
        <BOY>1885208</BOY>
        <EOY>2173582</EOY>
      </DeferredRevenue>
      <MortNotesPyblSecuredInvestProp>
        <BOY>4712827</BOY>
        <EOY>4612055</EOY>
      </MortNotesPyblSecuredInvestProp>
      <OtherLiabilities>
        <BOY>695664</BOY>
        <EOY>1016464</EOY>
      </OtherLiabilities>
      <TotalLiabilities>
        <BOY>7896177</BOY>
        <EOY>8450925</EOY>
      </TotalLiabilities>
      <FollowSFAS117>X</FollowSFAS117>
      <UnrestrictedNetAssets>
        <BOY>6673610</BOY>
        <EOY>7754869</EOY>
      </UnrestrictedNetAssets>
      <TemporarilyRestrictedNetAssets>
        <EOY>14492</EOY>
      </TemporarilyRestrictedNetAssets>
      <TotalNetAssetsFundBalances>
        <BOY>6673610</BOY>
        <EOY>7769361</EOY>
      </TotalNetAssetsFundBalances>
      <TotalLiabNetAssetsFundBalances>
        <BOY>14569787</BOY>
        <EOY>16220286</EOY>
      </TotalLiabNetAssetsFundBalances>
      <InfoInScheduleOPartXI>X</InfoInScheduleOPartXI>
      <ReconcilationRevenueExpenses>763881</ReconcilationRevenueExpenses>
      <ReconcilationOtherChanges>331870</ReconcilationOtherChanges>
      <InfoInScheduleOPartXII>X</InfoInScheduleOPartXII>
      <MethodOfAccountingAccrual>X</MethodOfAccountingAccrual>
      <AccountantCompileOrReview>0</AccountantCompileOrReview>
      <FSAudited>1</FSAudited>
      <AuditCommittee>1</AuditCommittee>
      <FinancialStatementConsolidated>X</FinancialStatementConsolidated>
      <FederalGrantAuditRequired>0</FederalGrantAuditRequired>
    </IRS990>
    <IRS990ScheduleC documentId="RetDoc1039700001">
      <SubstantiallyAllDuesNondeduct>0</SubstantiallyAllDuesNondeduct>
      <OnlyInHouseLobbying>0</OnlyInHouseLobbying>
      <AgreeToCarryoverPriorYear>0</AgreeToCarryoverPriorYear>
      <DuesAssessments>2071508</DuesAssessments>
      <NonDedLobbyPoliticalCurrent>420026</NonDedLobbyPoliticalCurrent>
      <NonDedLobbyPoliticalTotal>420026</NonDedLobbyPoliticalTotal>
      <AggrAmtReportedInDuesNotices>638024</AggrAmtReportedInDuesNotices>
      <TaxableAmount>-217998</TaxableAmount>
    </IRS990ScheduleC>
    <IRS990ScheduleD documentId="RetDoc1040000001">
      <Land>
        <OtherCostOrOtherBasis>925873</OtherCostOrOtherBasis>
        <BookValue>925873</BookValue>
      </Land>
      <Buildings>
        <OtherCostOrOtherBasis>5121509</OtherCostOrOtherBasis>
        <Depreciation>936638</Depreciation>
        <BookValue>4184871</BookValue>
      </Buildings>
      <LeaseholdImprovements>
        <OtherCostOrOtherBasis>375943</OtherCostOrOtherBasis>
        <Depreciation>104031</Depreciation>
        <BookValue>271912</BookValue>
      </LeaseholdImprovements>
      <Equipment>
        <OtherCostOrOtherBasis>776286</OtherCostOrOtherBasis>
        <Depreciation>636426</Depreciation>
        <BookValue>139860</BookValue>
      </Equipment>
      <OtherLandBuildings>
        <OtherCostOrOtherBasis>401403</OtherCostOrOtherBasis>
        <Depreciation>334168</Depreciation>
        <BookValue>67235</BookValue>
      </OtherLandBuildings>
      <TotalOfBookValueLandBuildings>5589751</TotalOfBookValueLandBuildings>
      <OtherLiabilities>
        <Description>CUSTOMER DEPOSITS</Description>
        <Amount>51030</Amount>
      </OtherLiabilities>
      <OtherLiabilities>
        <Description>MISCELLANEOUS</Description>
        <Amount>60934</Amount>
      </OtherLiabilities>
      <OtherLiabilities>
        <Description>DUE TO (FROM)</Description>
        <Amount>904500</Amount>
      </OtherLiabilities>
      <TotalOfAmounts>1016464</TotalOfAmounts>
      <Form990ScheduleDPartXIV>
        <Explanation>MASSACHUSETTS DENTAL SOCIETY (MDS) FOLLOWS THE ACCOUNTING FOR UNCERTAINTY IN INCOME TAXES STANDARD WHICH REQUIRES MDS TO REPORT UNCERTAIN TAX POSITIONS, RELATED INTEREST AND PENALTIES, AND TO ADJUST THEIR ASSETS AND LIABILITIES RELATED TO UNRECOGNIZED TAX BENEFITS AND ACCRUED INTEREST AND PENALTIES ACCORDINGLY. AS OF APRIL 30, 2011, MDS DETERMINED THAT THERE ARE NO MATERIAL UNRECOGNIZED TAX BENEFITS TO REPORT. INFORMATION AND INCOME TAX RETURNS FILED FOR THE YEARS ENDED APRIL 30, 2010, 2009 AND 2008, REMAIN SUBJECT TO EXAMINATION BY THE INTERNAL REVENUE SERVICE AND MASSACHUSETTS STATE JURISDICTIONS.</Explanation>
      </Form990ScheduleDPartXIV>
    </IRS990ScheduleD>
    <IRS990ScheduleI documentId="RetDoc1041900001">
      <RecordsMaintained>1</RecordsMaintained>
      <RecipientTable>
        <RecipientNameBusiness>
          <BusinessNameLine1>MINUTEMAN REGIONAL VOCATIONAL TECH SCHOOL</BusinessNameLine1>
        </RecipientNameBusiness>
        <AddressUS>
          <AddressLine1>758 MARRET ROAD</AddressLine1>
          <City>LEXINGTON</City>
          <State>MA</State>
          <ZIPCode>02421</ZIPCode>
        </AddressUS>
        <IRCSection>170(B)(1)(A)(V)</IRCSection>
        <AmountOfCashGrant>8400</AmountOfCashGrant>
        <PurposeOfGrant>THESE GRANTS WERE IN ADDITION TO THE GRANTS MADE BY THE MDS FOUNDATION TO THESE SAME SCHOOLS FOR THEIR DENTAL HYGIENE PROGRAMS.</PurposeOfGrant>
      </RecipientTable>
      <RecipientTable>
        <RecipientNameBusiness>
          <BusinessNameLine1>DCD (DOCTORS CARING FOR DOCTORS)</BusinessNameLine1>
        </RecipientNameBusiness>
        <AddressUS>
          <AddressLine1>PO BOX 716</AddressLine1>
          <City>ANDOVER</City>
          <State>MA</State>
          <ZIPCode>01810</ZIPCode>
        </AddressUS>
        <IRCSection>170(B)(1)(A)(V)</IRCSection>
        <AmountOfCashGrant>46692</AmountOfCashGrant>
        <PurposeOfGrant>THESE GRANT MONIES SUPPORT THE ACITIVITIES OF THAT ORGANIZATION THAT WORKS IN CONJUNCTION WITH THE MDS WELL-BEING COMMITTEE. MDS HAS PAID OUT THIS GRANT FOR MANY YEARS AND IT IS PAID IN EQUAL MONTHLY INSTALLMENTS OVER THE COURSE OF THE FISCAL YEAR.</PurposeOfGrant>
      </RecipientTable>
      <TotalNbrOf501C3AndGovtGrants>7</TotalNbrOf501C3AndGovtGrants>
      <Form990ScheduleIPartIV>
        <Identifier>PROCEDURE FOR MONITORING GRANTS IN THE U.S.:</Identifier>
        <ReturnReference>PART I, LINE 2:</ReturnReference>
        <Explanation>SCHEDULE I, PART I, LINE 2: THESE GRANTS WERE TO PROVIDE FUNDING FOR A DENTAL HYGIENE PROGRAM AT SCHOOLS. THE SCHOOLS SUBMIT A REPORT BACK TO US ON HOW THE GRANT MONIES WERE SPENT.</Explanation>
      </Form990ScheduleIPartIV>
    </IRS990ScheduleI>
    <IRS990ScheduleJ documentId="RetDoc1042400001">
      <BoardOrCommitteeApproval>X</BoardOrCommitteeApproval>
      <SeverancePayment>0</SeverancePayment>
      <SupplementalNonqualRetirePlan>0</SupplementalNonqualRetirePlan>
      <EquityBasedCompArrangement>0</EquityBasedCompArrangement>
      <Form990ScheduleJPartII>
        <NamePerson>KATHY BOYCE</NamePerson>
        <BaseCompensationFilingOrg>156484</BaseCompensationFilingOrg>
        <CompBasedOnRelatedOrgs>0</CompBasedOnRelatedOrgs>
        <BonusFilingOrg>0</BonusFilingOrg>
        <BonusRelatedOrgs>0</BonusRelatedOrgs>
        <OtherCompensationFilingOrg>0</OtherCompensationFilingOrg>
        <OtherCompensationRelatedOrgs>0</OtherCompensationRelatedOrgs>
        <DeferredCompFilingOrg>0</DeferredCompFilingOrg>
        <DeferredCompRelatedOrgs>0</DeferredCompRelatedOrgs>
        <NontaxableBenefitsFilingOrg>14612</NontaxableBenefitsFilingOrg>
        <NontaxableBenefitsRelatedOrgs>0</NontaxableBenefitsRelatedOrgs>
        <TotalCompensationFilingOrg>171096</TotalCompensationFilingOrg>
        <TotalCompensationRelatedOrgs>0</TotalCompensationRelatedOrgs>
        <CompReportPrior990FilingOrg>0</CompReportPrior990FilingOrg>
        <CompReportPrior990RelatedOrgs>0</CompReportPrior990RelatedOrgs>
      </Form990ScheduleJPartII>
      <Form990ScheduleJPartII>
        <NamePerson>ROBERT BOOSE</NamePerson>
        <BaseCompensationFilingOrg>288159</BaseCompensationFilingOrg>
        <CompBasedOnRelatedOrgs>0</CompBasedOnRelatedOrgs>
        <BonusFilingOrg>0</BonusFilingOrg>
        <BonusRelatedOrgs>0</BonusRelatedOrgs>
        <OtherCompensationFilingOrg>0</OtherCompensationFilingOrg>
        <OtherCompensationRelatedOrgs>0</OtherCompensationRelatedOrgs>
        <DeferredCompFilingOrg>0</DeferredCompFilingOrg>
        <DeferredCompRelatedOrgs>0</DeferredCompRelatedOrgs>
        <NontaxableBenefitsFilingOrg>36937</NontaxableBenefitsFilingOrg>
        <NontaxableBenefitsRelatedOrgs>0</NontaxableBenefitsRelatedOrgs>
        <TotalCompensationFilingOrg>325096</TotalCompensationFilingOrg>
        <TotalCompensationRelatedOrgs>0</TotalCompensationRelatedOrgs>
        <CompReportPrior990FilingOrg>0</CompReportPrior990FilingOrg>
        <CompReportPrior990RelatedOrgs>0</CompReportPrior990RelatedOrgs>
      </Form990ScheduleJPartII>
      <Form990ScheduleJPartII>
        <NamePerson>KAREN RAFELD</NamePerson>
        <BaseCompensationFilingOrg>156540</BaseCompensationFilingOrg>
        <CompBasedOnRelatedOrgs>0</CompBasedOnRelatedOrgs>
        <BonusFilingOrg>0</BonusFilingOrg>
        <BonusRelatedOrgs>0</BonusRelatedOrgs>
        <OtherCompensationFilingOrg>0</OtherCompensationFilingOrg>
        <OtherCompensationRelatedOrgs>0</OtherCompensationRelatedOrgs>
        <DeferredCompFilingOrg>0</DeferredCompFilingOrg>
        <DeferredCompRelatedOrgs>0</DeferredCompRelatedOrgs>
        <NontaxableBenefitsFilingOrg>19974</NontaxableBenefitsFilingOrg>
        <NontaxableBenefitsRelatedOrgs>0</NontaxableBenefitsRelatedOrgs>
        <TotalCompensationFilingOrg>176514</TotalCompensationFilingOrg>
        <TotalCompensationRelatedOrgs>0</TotalCompensationRelatedOrgs>
        <CompReportPrior990FilingOrg>0</CompReportPrior990FilingOrg>
        <CompReportPrior990RelatedOrgs>0</CompReportPrior990RelatedOrgs>
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    </IRS990ScheduleJ>
    <IRS990ScheduleO documentId="RetDoc1044400001">
      <GeneralExplanation>
        <Identifier>FORM 990, PART VI, SECTION A, LINE 6</Identifier>
        <Explanation>THE ORGANIZATION'S MEMBERSHIP IS COMPRISED OF ORAL HEALTH CARE PROFESSIONALS IN MASSACHUSETTS.</Explanation>
      </GeneralExplanation>
      <GeneralExplanation>
        <Identifier>FORM 990, PART VI, SECTION A, LINE 7A</Identifier>
        <Explanation>THE ORGANIZATION'S MEMBERS ELECT THE DELEGATES, WHO REPRESENT THEM IN VOTING TO ELECT THE GOVERNING BODY, THE BOARD OF TRUSTEES.</Explanation>
      </GeneralExplanation>
      <GeneralExplanation>
        <Identifier>FORM 990, PART VI, SECTION A, LINE 7B</Identifier>
        <Explanation>THE ANNUAL MEETING OF DELEGATES HAS THE RIGHT TO ADDRESS ANY ITEMS OR ACTIONS TAKEN BY THE BOARD DURING THE YEAR.</Explanation>
      </GeneralExplanation>
      <GeneralExplanation>
        <Identifier>FORM 990, PART VI, SECTION B, LINE 11</Identifier>
        <Explanation>THE FORM 990 IS PROVIDED TO THE TRUSTEES BEFORE FILING. THE CFO REVIEWS THE RETURN PRIOR TO BEING FILED.</Explanation>
      </GeneralExplanation>
      <GeneralExplanation>
        <ReturnReference>FORM 990, PART VI, SECTION B, LINE 12</ReturnReference>
        <Explanation>ALL BOARD MEMBERS SIGN THE CONFLICT OF INTEREST POLICY AND ANY CONFLICTS ARE ANNOUNCED AT THE BEGINNING OF EACH BOARD MEETING.</Explanation>
      </GeneralExplanation>
      <GeneralExplanation>
        <ReturnReference>FORM 990, PART VI, SECTION B, LINE 15</ReturnReference>
        <Explanation>THE EXECUTIVE DIRECTOR'S COMPENSATION IS DETERMINED BY THE COMPENSATION COMMITTEE OF THE BOARD OF TRUSTEES. THE CHIEF FINANCIAL OFFICER'S SALARY IS DETERMINED BY THE EXECUTIVE DIRECTOR.</Explanation>
      </GeneralExplanation>
      <GeneralExplanation>
        <ReturnReference>FORM 990, PART VI, SECTION C, LINE 19</ReturnReference>
        <Explanation>THE ORGANIZATION MAKES ITS GOVERNING DOCUMENTS, CONFLICT OF INTEREST POLICY AND FINANCIAL STATEMENTS AVAILABLE TO THE PUBLIC UPON REQUEST.</Explanation>
      </GeneralExplanation>
      <GeneralExplanation>
        <Identifier>CHANGES IN NET ASSETS OR FUND BALANCES:</Identifier>
        <ReturnReference>FORM 990, PART XI, LINE 5:</ReturnReference>
        <Explanation>NET UNREALIZED GAINS ON INVESTMENTS: 152,584. ADUSTMENT FOR VALLEY DISTRICT INVESTMENTS 179,286. TOTAL TO FORM 990, PART XI, LINE 5: 331,870.</Explanation>
      </GeneralExplanation>
      <GeneralExplanation>
        <ReturnReference>FORM 990, PART XI, LINE 2C</ReturnReference>
        <Explanation>THE BOARD OF TRUSTEES ASSUMES RESPONSIBILITY FOR THE OVERSIGHT OF THE AUDIT OF ITS FINANCIAL STATEMENTS AND SELECTION OF THE INDEPENDENT AUDITOR.</Explanation>
      </GeneralExplanation>
    </IRS990ScheduleO>
    <IRS990ScheduleR documentId="RetDoc1043400001">
      <Form990ScheduleRPartI>
        <NameOfDisregardedEntity>
          <BusinessNameLine1>FIRMIN JOINT VENTURE LLC</BusinessNameLine1>
        </NameOfDisregardedEntity>
        <AddressUS>
          <AddressLine1>TWO WILLOW STREET SUITE 200</AddressLine1>
          <City>SOUTHBOROUGH</City>
          <State>MA</State>
          <ZIPCode>01745</ZIPCode>
        </AddressUS>
        <EIN>043446721</EIN>
        <PrimaryActivities>TO OWN MDS' PRINCIPAL PROPERTY</PrimaryActivities>
        <LegalDomicileState>MA</LegalDomicileState>
        <TotalIncome>916938</TotalIncome>
        <EOYAssets>5288992</EOYAssets>
        <DirectControllingEntityName>
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        <DirectControllingEntityName>
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        <DirectControllingEntityName>
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        <ShareOfEOYAssets>277989</ShareOfEOYAssets>
        <PercentageOwnership>1.00000</PercentageOwnership>
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      <ReceiptOfIntAnnRentsRoyalties>0</ReceiptOfIntAnnRentsRoyalties>
      <GiftGrantOrCapContrToOtherOrg>1</GiftGrantOrCapContrToOtherOrg>
      <GiftGrantOrCapContrFrOtherOrg>0</GiftGrantOrCapContrFrOtherOrg>
      <LoansOrGuaranteesToOtherOrg>0</LoansOrGuaranteesToOtherOrg>
      <LoansOrGuaranteesFromOtherOrg>0</LoansOrGuaranteesFromOtherOrg>
      <SaleOfAssetsToOtherOrg>0</SaleOfAssetsToOtherOrg>
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      <ExchangeOfAssets>0</ExchangeOfAssets>
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      <RentalOfFacilitiesFrOtherOrgs>0</RentalOfFacilitiesFrOtherOrgs>
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      <ReimbursementPaidToOtherOrg>1</ReimbursementPaidToOtherOrg>
      <ReimbursementPaidByOtherOrg>1</ReimbursementPaidByOtherOrg>
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      <OtherTransferFromOtherOrg>0</OtherTransferFromOtherOrg>
      <TransactionsRelatedOrgsTable>
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        <MethodOfAmtDetermination>AMOUNT OF CONTRIBUTION AWARDED</MethodOfAmtDetermination>
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      <TransactionsRelatedOrgsTable>
        <NameOfOtherOrganization>
          <BusinessNameLine1>MDS FOUNDATION INC</BusinessNameLine1>
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        <MethodOfAmtDetermination>VALUE OF SERVICES PROVIDED</MethodOfAmtDetermination>
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      <TransactionsRelatedOrgsTable>
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        <MethodOfAmtDetermination>AMOUNT DUE FROM MDSF</MethodOfAmtDetermination>
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      <TransactionsRelatedOrgsTable>
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          <BusinessNameLine1>MDS INSURANCE SERVICES INC</BusinessNameLine1>
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        <MethodOfAmtDetermination>AMOUNT DUE TO MDSIS</MethodOfAmtDetermination>
      </TransactionsRelatedOrgsTable>
      <TransactionsRelatedOrgsTable>
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        <MethodOfAmtDetermination>VALUE OF SERVICES PROVIDED</MethodOfAmtDetermination>
      </TransactionsRelatedOrgsTable>
    </IRS990ScheduleR>
  </ReturnData>
</Return>