-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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<SEC-DOCUMENT>0001445116-10-000029.txt : 20100917
<SEC-HEADER>0001445116-10-000029.hdr.sgml : 20100917
<ACCEPTANCE-DATETIME>20100917163450
ACCESSION NUMBER:		0001445116-10-000029
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20100914
FILED AS OF DATE:		20100917
DATE AS OF CHANGE:		20100917

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Hampden Bancorp, Inc.
		CENTRAL INDEX KEY:			0001375320
		STANDARD INDUSTRIAL CLASSIFICATION:	SAVINGS INSTITUTIONS, NOT FEDERALLY CHARTERED [6036]
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0630

	BUSINESS ADDRESS:	
		STREET 1:		19 HARRISON AVENUE
		CITY:			SPRINGFIELD
		STATE:			MA
		ZIP:			01102
		BUSINESS PHONE:		(413) 736-1812

	MAIL ADDRESS:	
		STREET 1:		19 HARRISON AVENUE
		CITY:			SPRINGFIELD
		STATE:			MA
		ZIP:			01102

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			INVESTORS OF AMERICA LIMITED PARTNERSHIP
		CENTRAL INDEX KEY:			0000904217

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-33144
		FILM NUMBER:		101078550

	BUSINESS ADDRESS:	
		STREET 1:		135 N MERAMEC
		CITY:			CLAYTON
		STATE:			MO
		ZIP:			63105
		BUSINESS PHONE:		3148544600

	MAIL ADDRESS:	
		STREET 1:		135 N MERAMEC
		CITY:			CLAYTON
		STATE:			MO
		ZIP:			63105

	FORMER NAME:	
		FORMER CONFORMED NAME:	DIERBERG FOUR LP
		DATE OF NAME CHANGE:	19930512
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-09-14</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0001375320</issuerCik>
        <issuerName>Hampden Bancorp, Inc.</issuerName>
        <issuerTradingSymbol>HBNK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000904217</rptOwnerCik>
            <rptOwnerName>INVESTORS OF AMERICA LIMITED PARTNERSHIP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>135 N MERAMEC</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CLAYTON</rptOwnerCity>
            <rptOwnerState>MO</rptOwnerState>
            <rptOwnerZipCode>63105</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2010-09-14</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>30000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>10.1</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>702000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <ownerSignature>
        <signatureName>James F. Dierberg, President of First Securities America, Inc., General Partner of Investors of America, Limited Partnership</signatureName>
        <signatureDate>2010-09-17</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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