-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 VCS1eSh+Ow3thY04+CZ5FH/7FEP0fPGqkxfNuVAaWcjBJW9ws6JbsOz106c3RgPW
 QXxuw7KP9mEHA/KeCkuYlg==

<SEC-DOCUMENT>0001010549-10-000823.txt : 20101223
<SEC-HEADER>0001010549-10-000823.hdr.sgml : 20101223
<ACCEPTANCE-DATETIME>20101223122139
ACCESSION NUMBER:		0001010549-10-000823
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20101222
FILED AS OF DATE:		20101223
DATE AS OF CHANGE:		20101223

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			ASHBAUGH WILLIAM M
		CENTRAL INDEX KEY:			0001182922

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	814-00061
		FILM NUMBER:		101271394

	MAIL ADDRESS:	
		STREET 1:		12900 PRESTON RD
		STREET 2:		STE 700
		CITY:			DALLAS
		STATE:			TX
		ZIP:			75230

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CAPITAL SOUTHWEST CORP
		CENTRAL INDEX KEY:			0000017313
		IRS NUMBER:				751072796
		STATE OF INCORPORATION:			TX
		FISCAL YEAR END:			0331

	BUSINESS ADDRESS:	
		STREET 1:		12900 PRESTON RD STE 700
		CITY:			DALLAS
		STATE:			TX
		ZIP:			75230
		BUSINESS PHONE:		9722338242

	MAIL ADDRESS:	
		STREET 1:		12900 PRESTON RD
		STREET 2:		SUITE 700
		CITY:			DALLAS
		STATE:			TX
		ZIP:			75230
</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>2010-12-22</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000017313</issuerCik>
        <issuerName>CAPITAL SOUTHWEST CORP</issuerName>
        <issuerTradingSymbol>CSWC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001182922</rptOwnerCik>
            <rptOwnerName>ASHBAUGH WILLIAM M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>12900 PRESTON RD</rptOwnerStreet1>
            <rptOwnerStreet2>STE 700</rptOwnerStreet2>
            <rptOwnerCity>DALLAS</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>75230</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Senior Vice President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2010-12-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>5218</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>65.7</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5218</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Incentive Stock Option</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>65.7</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2010-12-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>5218</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>65.7</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2002-08-27</value>
            </exerciseDate>
            <expirationDate>
                <value>2011-08-28</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>6718</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1500</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Exercisable in ten (10) annual cumulative installments of 1,500 shares granted 8/27/01.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ William M. Ashbaugh</signatureName>
        <signatureDate>2010-12-23</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----