Explorer Coinvest SC 13D Booz Allen Hamilton Holding / EXPLORER COINVEST ownership change

Exhibit 99.1

Joint Filing Agreement

      The undersigned hereby agree that they are filing this statement jointly pursuant to Rule 13d-1(k)(1). Each of them is responsible for the timely filing of such Schedule 13D and any amendments thereto, and for the completeness and accuracy of the information concerning such person contained therein; but none of them is responsible for the completeness or accuracy of the information concerning the other persons making the filing, unless such person knows or has reason to believe that such information is inaccurate.

     In accordance with Rule 13d-1(k)(1) promulgated under the Securities and Exchange Act of 1934, as amended, the undersigned hereby agree to the joint filing with each other on behalf of each of them of such a statement on Schedule 13D with respect to the common stock beneficially owned by each of them, of Booz Allen Hamilton Holding Corporation, a Delaware corporation. This Joint Filing Agreement shall be included as an exhibit to such Schedule 13D.

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IN WITNESS WHEREOF, the undersigned hereby execute this Joint Filing Agreement as of the 14^th day of December, 2010.

EXPLORER COINVEST, LLC
By:	Carlyle Partners V US, L.P., as its Managing Member
By:	TC Group V US, L.P., as its General Partner
By:	TC Group V US, L.L.C., as its General Partner
By:	TC Group Investment Holdings, L.P., as its Managing Member
By:	TCG Holdings II, L.P., as its General Partner
By:	DBD Investors V, L.L.C., as its General Partner
By:	/s/ Daniel A. D’Aniello
	Name: Daniel A. D’Aniello
	Title:   Managing Director
CARLYLE PARTNERS V US, L.P.
By:	TC Group V US, L.P., as its General Partner
By:	TC Group V US, L.L.C., as its General Partner
By:	TC Group Investment Holdings, L.P., as its Managing Member
By:	TCG Holdings II, L.P., as its General Partner
By:	DBD Investors V, L.L.C., as its General Partner
By:	/s/ Daniel A. D’Aniello
	Name: Daniel A. D’Aniello
	Title:   Managing Director

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TC GROUP V US, L.P.
By:	TC Group V US, L.L.C., as its General Partner
By:	TC Group Investment Holdings, L.P., as its Managing Member
By:	TCG Holdings II, L.P., as its General Partner
By:	DBD Investors V, L.L.C., as its General Partner
By:	/s/ Daniel A. D’Aniello
	Name: Daniel A. D’Aniello
	Title:   Managing Director
TC GROUP V US, L.L.C.
By:	TC Group Investment Holdings, L.P., as its Managing Member
By:	TCG Holdings II, L.P., as its General Partner
By:	DBD Investors V, L.L.C., as its General Partner
By:	/s/ Daniel A. D’Aniello
	Name: Daniel A. D’Aniello
	Title:   Managing Director
TC GROUP INVESTMENT HOLDINGS, L.P.
By:	TCG Holdings II, L.P., as its General Partner
By:	DBD Investors V, L.L.C., as its General Partner
By:	/s/ Daniel A. D’Aniello
	Name: Daniel A. D’Aniello
	Title:   Managing Director

3

TCG HOLDINGS II, L.P.
By:	DBD Investors V, L.L.C., as its General Partner
By:	/s/ Daniel A. D’Aniello
	Name: Daniel A. D’Aniello
	Title:   Managing Director
DBD INVESTORS V, L.L.C.
By:	/s/ Daniel A. D’Aniello
	Name: Daniel A. D’Aniello
	Title:   Managing Director
*
Ralph W. Shrader
*
CG Appleby
*
Joseph E. Garner
*
Francis J. Henry, Jr.
*
Lloyd Howell, Jr.
*
Joseph Logue
*
Joseph W. Mahaffee
*
John D. Mayer

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*

John M. McConnell

*

Robert S. Osborne

*

Patrick F. Peck

*

Horacio D. Rozanski

*

Samuel R. Strickland

* The undersigned, by signing his name hereto, executes this Agreement pursuant to the Power of Attorney executed on behalf of the above-named individuals.

By:	/s/ Terrence Kaden
	Terrence Kaden Attorney-in-Fact

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