Exhibit 3.21

CERTIFICATE OF FORMATION

OF

GLOBAL LINGUIST SOLUTIONS LLC

     1. The name of the limited liability company is Global Nation Building LLC.

     2. The address of its initial registered office in the State of Delaware is Corporation Trust Center, 1209 Orange Street, in the City of Wilmington, County of New Castle The name of its registered agent at such address is The Corporation Trust Company.

     IN WITNESS WHEREOF, the undersigned has executed this Certificate of Formation of Global Linguist Solutions LLC this 20th day of July, 2006.

/s/ H. Montgomery Hougen  

H. Montgomery Hougen 

Vice President, Secretary & Deputy General
     Counsel
DynCorp International LLC