<?xml version="1.0"?><ownershipDocument><schemaVersion>X0201</schemaVersion>    <documentType>4</documentType><periodOfReport>2003-10-01</periodOfReport><notSubjectToSection16>0</notSubjectToSection16><issuer><issuerCik>0001023313</issuerCik><issuerName>FORRESTER RESEARCH INC</issuerName>        <issuerTradingSymbol>FORR</issuerTradingSymbol></issuer><reportingOwner><reportingOwnerId><rptOwnerCik>0001206310</rptOwnerCik><rptOwnerName>BELANGER RICHARD</rptOwnerName></reportingOwnerId><reportingOwnerAddress><rptOwnerStreet1>C/O FORRESTER RESEARCH</rptOwnerStreet1><rptOwnerStreet2>400 TECHNOLOGY SQUARE</rptOwnerStreet2><rptOwnerCity>CAMBRIDGE</rptOwnerCity><rptOwnerState>MA</rptOwnerState><rptOwnerZipCode>02139</rptOwnerZipCode><rptOwnerStateDescription></rptOwnerStateDescription></reportingOwnerAddress><reportingOwnerRelationship><isDirector>0</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>Chief Technology Officer</officerTitle></reportingOwnerRelationship></reportingOwner><derivativeTable><derivativeTransaction><securityTitle><value>Non-Qualified Stock Option (right to buy)</value></securityTitle><conversionOrExercisePrice><value>13.94</value></conversionOrExercisePrice><transactionDate><value>2003-10-01</value></transactionDate><deemedExecutionDate><value>2003-10-01</value></deemedExecutionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>6000</value></transactionShares><transactionPricePerShare><value>13.94</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><footnoteId id="F1" /></exerciseDate><expirationDate><value>2013-09-30</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>6000</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>6000</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership></ownershipNature></derivativeTransaction></derivativeTable><footnotes><footnote id="F1">The options become exercisable on the first anniversary of the grant date.</footnote></footnotes><ownerSignature><signatureName>/s/ Kimberly Maxwell (Attorney in fact for Richard Belanger)</signatureName><signatureDate>2003-10-01</signatureDate></ownerSignature></ownershipDocument>

