<SUBMISSION>
<ACCESSION-NUMBER>0001069258-08-000003
<TYPE>3
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20080628
<FILING-DATE>20080707
<DATE-OF-FILING-DATE-CHANGE>20080707
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>KRATOS DEFENSE & SECURITY SOLUTIONS, INC.
<CIK>0001069258
<ASSIGNED-SIC>4899
<IRS-NUMBER>133818604
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1228
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>4810 EASTGATE MALL
<STREET2>.
<CITY>SAN DIEGO
<STATE>CA
<ZIP>92121
<PHONE>858-812-7300
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>4810 EASTGATE MALL
<STREET2>.
<CITY>SAN DIEGO
<STATE>CA
<ZIP>92121
</MAIL-ADDRESS>
<FORMER-COMPANY>
<FORMER-CONFORMED-NAME>WIRELESS FACILITIES INC
<DATE-CHANGED>19990817
</FORMER-COMPANY>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>LAKE EDWARD M
<CIK>0001259943
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>3
<ACT>34
<FILE-NUMBER>000-27231
<FILM-NUMBER>08941744
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>SYS TECHNOLOGIES
<STREET2>5050 MURPHY CANYON RD STE 200
<CITY>SAN DIEGO
<STATE>CA
<ZIP>92123
<PHONE>858-715-5500
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>5050 MURPHY CANYON ROAD
<STREET2>SUITE 2000
<CITY>SAN DIEGO
<STATE>CA
<ZIP>92123
</MAIL-ADDRESS>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0203</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2008-06-28</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001069258</issuerCik>
        <issuerName>KRATOS DEFENSE &amp; SECURITY SOLUTIONS, INC.</issuerName>
        <issuerTradingSymbol>KTOS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001259943</rptOwnerCik>
            <rptOwnerName>LAKE EDWARD M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>5050 MURPHY CANYON ROAD</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 2000</rptOwnerStreet2>
            <rptOwnerCity>SAN DIEGO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>92123</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Vice President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>33957</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Edward M. &amp; Stina I Lake JT TEN</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>6291</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Edward M. Lake and Stina Sundberg Lake JTWROS</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>40885</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Convertible Note</value>
                <footnoteId id="F2"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>2.86</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2006-02-14</value>
            </exerciseDate>
            <expirationDate>
                <value>2009-02-14</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>8736</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Common stock of Issuer issued to reporting person in exchange for shares of SYS surrendered by reporting person in connection with Issuer's acquisition of SYS on June 28, 2008 at an exchange rate of 1.2582 shares of Issuer's common stock for each share of SYS common stock.</footnote>
        <footnote id="F2">Convertible Note assumed by Issuer in connection with its acquisition of SYS on June 28, 2008.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Edward M. Lake, by Matthew G. Colvin, Attorney-In-Fact</signatureName>
        <signatureDate>2008-07-07</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
