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As filed with the Securities and Exchange Commission on March 10, 2010

Registration No. 333-152671

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

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Amendment No. 4
to
FORM S-1
REGISTRATION STATEMENT
UNDER
THE SECURITIES ACT OF 1933

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First Wind Holdings Inc.
(Exact Name of Registrant as Specified in Its Charter)

179 Lincoln Street, Suite 500
Boston, MA 02111
617-960-2888
(Address, Including Zip Code, and Telephone Number, Including Area Code, of Registrant's Principal Executive Offices)

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Paul Gaynor
Chief Executive Officer
First Wind Holdings Inc.
179 Lincoln Street, Suite 500
Boston, MA 02111
617-960-2888
(Name, Address, Including Zip Code, and Telephone Number, Including Area Code, of Agent For Service)

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Copies to:

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Approximate date of commencement of proposed sale to the public:
As soon as practicable after this Registration Statement is declared effective.

          If any 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.    o

          If this form is filed to register additional securities for an offering pursuant to Rule 462(b) 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.    o

          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.    o

          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 statement number of the earlier effective registration statement for the same offering.    o

          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 definitions of "large accelerated filer," "accelerated filer," and "smaller reporting company" in Rule 12b 2 of the Exchange Act. (Check one):

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          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 or until this registration statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.

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Explanatory Note

        This Amendment No. 4 is being filed solely for the purpose of filing the exhibits indicated in Item 16 of Part II of the Registration Statement. No change is made to the prospectus constituting Part I of the Registration Statement or Items 13, 14, 15 and 17 of Part II of the Registration Statement.

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PART II

INFORMATION NOT REQUIRED IN THE PROSPECTUS

Item 13.    Other Expenses of Issuance and Distribution

        Set forth below are the expenses (other than underwriting discounts and commissions) expected to be incurred in connection with the issuance and distribution of the securities registered hereby. With the exception of the SEC registration fee and the FINRA filing fee, the amounts set forth below are estimates.

Item 14.    Indemnification of Officers and Directors

        Our certificate of incorporation provides that a director will not be liable to the corporation or its stockholders for monetary damages for breach of fiduciary duty as a director, except for liability (1) for any breach of the director's duty of loyalty to the corporation or its stockholders, (2) for acts or omissions not in good faith or which involved intentional misconduct or a knowing violation of the law, (3) under section 174 of the DGCL for unlawful payment of dividends or improper redemption of stock or (4) for any transaction from which the director derived an improper personal benefit. In addition, if the DGCL is amended to authorize the further elimination or limitation of the liability of directors, then the liability of a director of the corporation, in addition to the limitation on personal liability provided for in our certificate of incorporation, will be limited to the fullest extent permitted by the amended DGCL. Our bylaws provide that the corporation will indemnify, and advance expenses to, any officer or director to the fullest extent authorized by the DGCL.

        Section 145 of the DGCL provides that a corporation may indemnify directors and officers as well as other employees and individuals against expenses, including attorneys' fees, judgments, fines and amounts paid in settlement in connection with specified actions, suits and proceedings whether civil, criminal, administrative, or investigative, other than a derivative action by or in the right of the corporation, if they acted in good faith and in a manner they reasonably believed to be in or not opposed to the best interests of the corporation and, with respect to any criminal action or proceeding, had no reasonable cause to believe their conduct was unlawful. A similar standard is applicable in the case of derivative actions, except that indemnification extends only to expenses, including attorneys' fees, incurred in connection with the defense or settlement of such action and the statute requires court approval before there can be any indemnification where the person seeking indemnification has been found liable to the corporation. The statute provides that it is not exclusive of other indemnification that may be granted by a corporation's certificate of incorporation, bylaws, disinterested director vote, stockholder vote, agreement or otherwise.

        Our certificate of incorporation also contains indemnification rights for our directors and our officers. Specifically, our certificate of incorporation provides that we shall indemnify our officers and

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directors to the fullest extent authorized by the DGCL. Further, we may maintain insurance on behalf of our officers and directors against expense, liability or loss asserted incurred by them in their capacities as officers and directors.

        We have obtained directors' and officers' insurance to cover our directors, officers and some of our employees for certain liabilities.

        We will enter into written indemnification agreements with our directors and executive officers. Under these proposed agreements, if an officer or director makes a claim of indemnification to us, either a majority of the independent directors or independent legal counsel selected by the independent directors must review the relevant facts and make a determination whether the officer or director has met the standards of conduct under Delaware law that would permit (under Delaware law) and require (under the indemnification agreement) us to indemnify the officer or director.

Item 15.    Recent Sales of Unregistered Securities

        In connection with its formation in May 2008, First Wind Holdings Inc. issued one share of its common stock to First Wind Holdings, LLC. The share was issued in reliance upon an exemption from registration afforded by Section 4(2) of the Securities Act. No underwriters, brokers or finders were involved in this issuance. The single share was issued by First Wind Holdings Inc. to First Wind Holdings, LLC in order to form First Wind Holdings Inc. and did not involve a public offering, which would require registration under the Securities Act of 1933.

        Since January 1, 2007, First Wind Holdings, LLC has granted to directors, officers and employees an aggregate of 95,744,117 Series B Units (consisting of Series B-2, B-3 and B-4 Units), of which 23,695,334 such Series B Units have been forfeited or cancelled. The issuances of the Series B Units to directors, officers and employees were deemed to be exempt from registration under the Securities Act in reliance on Rule 701 as promulgated under the Securities Act.

        In addition, during the past three years, First Wind Holdings, LLC issued unregistered securities to the entities and persons described below. None of these transactions involved any underwriters or any public offerings, and we believe that each of these transactions was exempt from registration requirements pursuant to Section 3(a)(9) or Section 4(2) of the Securities Act of 1933, as amended. The recipients of the securities in these transactions represented their intention to acquire the securities for investment only and not with a view to or for sale in connection with any distribution thereof. The share numbers presented below do not give effect to the reorganization transactions described in the prospectus.

        During the fiscal year ended December 31, 2007, First Wind Holdings, LLC issued the following unregistered securities for the consideration listed:

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*

To be filed by amendment.

**

Previously filed.

†

Certain portions of this exhibit have been omitted by redacting a portion of the text (indicated by asterisks in the text). This exhibit has been filed separately with the Securities and Exchange Commission pursuant to a request for confidential treatment.

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*

To be filed by amendment.

**

Previously filed.

†

Certain portions of this exhibit have been omitted by redacting a portion of the text (indicated by asterisks in the text). This exhibit has been filed separately with the Securities and Exchange Commission pursuant to a request for confidential treatment.