<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2006-11-21</periodOfReport>

    <dateOfOriginalSubmission>2006-11-22</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001364541</issuerCik>
        <issuerName>Eagle Rock Energy Partners, L.P.</issuerName>
        <issuerTradingSymbol>EROC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001251939</rptOwnerCik>
            <rptOwnerName>FITZGERALD RICHARD W</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>14950 HEATHROW FOREST PARKWAY, SUITE 111</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>HOUSTON</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77032</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Senior VP &amp; CFO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Units representing limited partner interests</value>
            </securityTitle>
            <transactionDate>
                <value>2006-11-21</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>316</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>17.765</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>545</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See note (1)</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">On October 27, 2006, in connection with the Issuer's initial public offering of common units representing limited partner interests, Eagle Rock Holdings, L.P. (&quot;Holdings&quot;) contributed assets to the Issuer and received 3,459,236 common units and 20,691,495 subordinated units. On November 21, 2006, 1,271,365 common units were redeemed from Holdings in connection with the underwriters' exercise of their option to purchase additional shares, leaving Holdings with a total of 2,187,871 common units. The reporting person owns 0.02% of Holdings, and thus indirectly owns 545 common units and 5,150 subordinated units through his ownership in Holdings. The reporting person disclaims beneficial ownership of the reported securities except to the extent of his pecuniary interests therein, and this report shall not be deemed an admission that the reporting person is the beneficial owner of the reported securities for purposes of Section 16 or for any other purpose.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Richard W. FitzGerald</signatureName>
        <signatureDate>2006-12-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
