SI International on Winning Team Supporting DoD Washington Headquarters Services

Oct. 22, 2007

RESTON, Va., Oct. 22 /PRNewswire-FirstCall/ -- SI International, Inc. (Nasdaq: SINT), an information technology and network solutions (IT) company, announced today that it is a member of the KT Consulting, Inc. team that has been awarded the Information Technology Services, Program Support Services Contract with the Department of Defense (DoD) Washington Headquarters Services (WHS). The contract has a one-year base period and four one-year options with an estimated value of $70 million. Over the five-year period, the contract is anticipated to have a value of approximately $28 million to SI International. The value of the contract win was included in the October 11, 2007 news release announcing awards in excess of $450 million for the month of September.

The 2,500 civilian, military, and contractor personnel of the WHS manage DoD-wide programs and operations for the Pentagon Reservation and DoD leased facilities in the National Capital Area. The contract will function as a vehicle to accelerate and consolidate the enterprise infrastructure platform enabling enhanced sustainment of all WHS organizations. The KT Consulting and SI International team will provide program and performance management; network, systems, and web administration; engineering support; application and software development; information assurance and security; and disaster recovery support.

About SI International: SI International, a member of the Russell 2000 and S&P SmallCap 600 indices, is a provider of information technology and network solutions (IT) primarily to the federal government. The Company combines technology and industry expertise to provide a full spectrum of state-of-the- practice solutions and services, from design and development to documentation and operations, to assist clients in achieving their missions. SI International is ranked as the 42nd largest Federal Prime IT Contractor by Washington Technology and has approximately 4,700 employees. More information about SI International can be found at http://www.si-intl.com.

The above-referenced statements may contain forward-looking statements that are made pursuant to the safe-harbor provisions of the Private Securities Litigation Reform Act of 1995. Expressions of future goals, financial information or reporting, and similar expressions reflecting something other than historical fact are intended to identify forward-looking statements, but are not the exclusive means of identifying such statements. These forward- looking statements may involve a number of risks and uncertainties, which are described in the Company's filings with the Securities and Exchange Commission. These risks and uncertainties include: changes in federal government (or other applicable) procurement laws, regulations, policies and budgets; risks relating to contract performance; changes in the competitive environment (including as a result of bid protests); and the important factors discussed in the Risk Factors section of the annual report on Form 10-K filed by the Company with the Securities and Exchange Commission and available directly from the Commission at www.sec.gov. The actual results may differ materially from any forward-looking statements due to such risks and uncertainties. The Company undertakes no obligations to revise or update any forward-looking statements in order to reflect events or circumstances that may arise after the date of this release.

Contact: Alan Hill VP, Corp. Communications 703-234-6854 [email protected]

SOURCE SI International, Inc.

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