As filed with the Securities and Exchange Commission on November 19, 2009

Registration No. 333-161719 

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

AMENDMENT NO. 7 TO FORM S-1

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

GLOBAL DEFENSE TECHNOLOGY & SYSTEMS, INC.

(Exact name of registrant as specified in its charter)

1501 Farm Credit Drive, Suite 2300

McLean, Virginia 22102-5011

(703) 738-2840

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

John Hillen

Chief Executive Officer

Global Defense Technology & Systems, Inc.

1501 Farm Credit Drive, Suite 2300

McLean, Virginia 22102-5011

(703) 738-2840

(Name, address including zip code, and telephone number, including area code, of agent for service)

Copies to:

Approximate date of commencement of proposed sale to the public:

As soon as practicable after the effective date of this Registration Statement

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, as amended (the Securities Act) check the following box:  ¨

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ¨

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ¨

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration number of the earlier effective registration statement for the same offering.  ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until the Registration Statement shall become effective on such date as the Securities and Exchange Commission (the SEC), acting pursuant to such Section 8(a), may determine.

EXPLANATORY NOTE

We are filing this Amendment No. 7 to Form S-1 to correct typographical errors contained in Amendment No. 6 to Form S-1, Exhibit 23.1, Consent of Independent Registered Public Accounting Firm, and Exhibit 23.2, Consent of Independent Registered Public Accounting Firm.

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

Item 13. Other Expenses of Issuance and Distribution

The following table itemizes the expenses, other than the underwriting discount, incurred, or to be incurred, by us in connection with the registration and issuance of the securities being registered hereunder. All amounts shown below are estimates except for the SEC registration fee and the NASD filing fee.

We will bear all expenses shown above.

Item 14. Indemnification of Directors and Officers

As permitted by the Delaware General Corporation Law, our amended and restated certificate of incorporation includes provisions that eliminate the personal liability of our directors for monetary damages for breach of fiduciary duty as a director, except for liability:

Our amended and restated bylaws further provide for the indemnification of our directors and officers to the fullest extent permitted by Section 145 of the Delaware General Corporation Law. Section 145 of the Delaware General Corporation Law authorizes a court to award, or a corporation’s board of directors to grant, indemnity to directors and officers in terms sufficiently broad to permit such indemnification under certain circumstances for liabilities (including reimbursement for expenses incurred) arising under the Securities Act of 1933, as amended, which we refer to as the Securities Act.

Our directors and officers are covered by insurance policies indemnifying against certain liabilities, including certain liabilities arising under the Securities Act, which might be incurred by them in such capacities and against which they cannot be indemnified by us.

In addition, the Registrant has entered into indemnity agreements with each of its current directors and officers. These agreements provide for the indemnification of the Registrant’s officers and directors for all expenses and liabilities incurred in connection with any action or proceeding brought against them by reason of the face that they are or were agents of the Registrant. At present, there is no pending litigation or proceeding involving a director, officer or employee of the Registrant regarding which indemnification is sought, nor is the Registrant aware of any threatened litigation that may result in claims for indemnification.

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The indemnification provisions in the Registrant’s amended and restated certificate of incorporation and amended and restated bylaws and the indemnity agreements entered into between the Registrant and each of its directors and officers may be sufficiently broad to permit indemnification of the Registrant’s directors and officers for liabilities arising under the Securities Act.

Additionally, reference is made to the indemnification provisions of the Underwriting Agreement filed as Exhibit 1.1 hereto.

Item 15. Recent Sales of Unregistered Securities

None.

Item 16. Exhibits and Financial Statement Schedules

(a) The following Exhibits are filed herewith and made a part hereof:

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(b) All financial statement schedules have been omitted because the information required to be presented in them are not applicable or is shown in the consolidated financial statements or notes thereto.

Item 17. Undertakings

(a) The undersigned hereby undertakes:

(b) The undersigned hereby undertakes to provide to the underwriters at the closing specified in the underwriting agreement, certificates in such denominations and registered in such names as required by the underwriters to permit prompt delivery to each purchaser.

Insofar as indemnification for liabilities arising under the Securities Act may be permitted to directors, officers, and controlling persons of the registrant pursuant to the foregoing provisions, or otherwise, the registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer, or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Act and will be governed by the final adjudication of such issue.

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SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, the registrant has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the city of McLean, Commonwealth of Virginia, on November 19, 2009.

Pursuant to the requirements of the Securities Act, this Registration Statement has been signed below by the following persons in the capacities and on the dates indicated.

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INDEX TO EXHIBITS

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