CUSIP No. 969199108 13G Page 1 of 13 Pages UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 ---------------------- SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. _________)* Willbros Group, Inc. (Name of Issuer) Common Stock, $.05 par value per share (Title of Class of Securities) 969199108 (CUSIP Number) October 29, 2005 (Date of Event Which Requires Filing of this statement) Check the appropriate box to designate the rule pursuant to which this Schedule is filed: [ ] Rule 13d-1(b) [X] Rule 13d-1(c) [ ] Rule 13d-1(d) ---------------- *The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page. The information required in the remainder of this cover page shall not be deemed to be "filed" for purposes of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes). CUSIP No. 969199108 13G Page 2 of 13 Pages ----------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) GLG North American Opportunity Fund ----------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS) (a) [X] (b) [ ] ----------------------------------------------------------------------- (3) SEC USE ONLY ----------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION Cayman Islands ----------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER 0 SHARES ------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 1,245,500 shares of Common Stock OWNED BY ------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER 0 REPORTING ------------------------------------------------------------- PERSON WITH: (8) SHARED DISPOSITIVE POWER 1,245,500 shares of Common Stock ----------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,245,500 shares of Common Stock ----------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS) [ ] ----------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 5.78% ----------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) PN ----------------------------------------------------------------------- CUSIP No. 969199108 13G Page 3 of 13 Pages ----------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) GLG Partners LP ----------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS) (a) [X] (b) [ ] ----------------------------------------------------------------------- (3) SEC USE ONLY ----------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION England ----------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER 0 SHARES ------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 1,976,780 shares of Common Stock OWNED BY ------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER 0 REPORTING ------------------------------------------------------------- PERSON WITH: (8) SHARED DISPOSITIVE POWER 1,976,780 shares of Common Stock ----------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,976,780 shares of Common Stock ----------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS) [ ] ----------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 9.17% ----------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) PN ----------------------------------------------------------------------- CUSIP No. 969199108 13G Page 4 of 13 Pages ----------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) GLG Partners Limited ----------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS) (a) [X] (b) [ ] ----------------------------------------------------------------------- (3) SEC USE ONLY ----------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION England ----------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER 0 SHARES ------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 1,976,780 shares of Common Stock OWNED BY ------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER 0 REPORTING ------------------------------------------------------------- PERSON WITH: (8) SHARED DISPOSITIVE POWER 1,976,780 shares of Common Stock ----------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,976,780 shares of Common Stock ----------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS) [ ] ----------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 9.17% ----------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) OO ----------------------------------------------------------------------- CUSIP No. 969199108 13G Page 5 of 13 Pages ----------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) Noam Gottesman ----------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS) (a) [X] (b) [ ] ----------------------------------------------------------------------- (3) SEC USE ONLY ----------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION United States ----------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER 0 SHARES ------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 1,976,780 shares of Common Stock OWNED BY ------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER 0 REPORTING ------------------------------------------------------------- PERSON WITH: (8) SHARED DISPOSITIVE POWER 1,976,780 shares of Common Stock ----------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,976,780 shares of Common Stock ----------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS) [ ] ----------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 9.17% ----------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) IN ----------------------------------------------------------------------- CUSIP No. 969199108 13G Page 6 of 13 Pages ----------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) Pierre Lagrange ----------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS) (a) [X] (b) [ ] ----------------------------------------------------------------------- (3) SEC USE ONLY ----------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION Belgium ----------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER 0 SHARES ------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 1,976,780 shares of Common Stock OWNED BY ------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER 0 REPORTING ------------------------------------------------------------- PERSON WITH: (8) SHARED DISPOSITIVE POWER 1,976,780 shares of Common Stock ----------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,976,780 shares of Common Stock ----------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS) [ ] ----------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 9.17% ----------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) IN ----------------------------------------------------------------------- CUSIP No. 969199108 13G Page 7 of 13 Pages (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) Emmanuel Roman ----------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS) (a) [X] (b) [ ] ----------------------------------------------------------------------- (3) SEC USE ONLY ----------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION France ----------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER 0 SHARES ------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 1,976,780 shares of Common Stock OWNED BY ------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER 0 REPORTING ------------------------------------------------------------- PERSON WITH: (8) SHARED DISPOSITIVE POWER 1,976,780 shares of Common Stock ----------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,976,780 shares of Common Stock ----------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS) [ ] ----------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 9.17% ----------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) IN ----------------------------------------------------------------------- CUSIP No. 969199108 13G Page 8 of 13 Pages Item 1. (a) Name of Issuer Willbros Group, Inc., a Republic of Panama corporation (the "Company"). (b) Address of Issuer's Principal Executive Offices 2000 Building 50th Street, 8th Floor P. O. Box 0816-01098 Panama, Republic of Panama Item 2(a). Name of Person Filing Item 2(b). Address of Principal Business Office or, if none, Residence Item 2(c). Citizenship GLG North American Opportunity Fund c/o GLG Partners LP 1 Curzon Street London W1J 5HB England Citizenship: Cayman Islands GLG Partners LP 1 Curzon Street London W1J 5HB England Citizenship: England GLG Partners Limited c/o GLG Partners LP 1 Curzon Street London W1J 5HB England Citizenship: England Noam Gottesman c/o GLG Partners LP 1 Curzon Street London W1J 5HB England Citizenship: United States Pierre Lagrange c/o GLG Partners LP 1 Curzon Street London W1J 5HB England Citizenship: Belgium Emmanuel Roman c/o GLG Partners LP 1 Curzon Street London W1J 5HB England Citizenship: France CUSIP No. 969199108 13G Page 9 of 13 Pages Item 2(d) Title of Class of Securities Common Stock, $.05 par value per share ("Common Stock") Item 2(e) CUSIP Number 969199108 Item 3. If this statement is filed pursuant to ss.ss.240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a: (a)[ ] Broker or dealer registered under Section 15 of the Act (15 U.S.C. 78o). (b)[ ] Bank as defined in Section 3(a)(6) of the Act (15 U.S.C. 78c). (c)[ ] Insurance company as defined in Section 3(a)(19) of the Act (15 U.S.C. 78c). (d)[ ] Investment company registered under Section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8). (e)[ ] An investment adviser in accordance with ss.240.13d-1(b)(1)(ii)(E); (f)[ ] An employee benefit plan or endowment fund in accordance with ss.240.13d-1(b)(1)(ii)(F); (g)[ ] A parent holding company or control person in accordance with ss.240.13d-1(b)(1)(ii)(G); (h)[ ] A savings association as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813); (i)[ ] A church plan that is excluded from the definition of an investment company under Section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3); (j)[ ] Group, in accordance with Rule 13d-1(b)(1)(ii)(J). Item 4. Ownership Provide the following information regarding the aggregate number and percentage of the class of securities of the issuer identified in Item 1. (a) Amount beneficially owned: As of the date of this filing, GLG Partners LP, GLG Partners Limited, Noam Gottesman, Pierre Lagrange, and Emmanuel Roman may be deemed the beneficial owner of (i) 1,245,500 shares of Common Stock held by GLG North American Opportunity Fund, (ii) 82,500 shares of Common Stock held by GLG Investments plc, through its subfund, GLG North American Equity Fund, (iii) 6,724 shares of Common Stock held by Lyxor/GLG Pan European Equity Fund Ltd, (iv) 16,100 shares of Common Stock held by The Century Fund SICAV, (v) 15,651 shares of Common Stock held by GLG Equities Long-Short CI, (vi) 25,662 shares of Common Stock held by Lyxor/GLG North American Alternative Equity Fund Ltd , (vii) 8,543 shares of Common Stock held by Citi GLG North American Fund Ltd, (viii) 174,100 shares of Common Stock held by GLG Global Aggressive Fund, (ix) 196,980 shares of Common Stock held by GLG European Long-Short Fund, and (x) 205,020 shares of CUSIP No. 969199108 13G Page 10 of 13 Pages Common Stock held by GLG Global Utilities Fund (each entity referred to in (i) through (x) is herein referred to as a "Fund" and, collectively, as the "Funds"). GLG Partners LP, an English limited partnership, acts as the investment manager of each of the Funds and has voting and dispositive power over the securities held by the Funds. The general partner of GLG Partners LP is GLG Partners Limited, an English limited company. The shareholders of GLG Partners Limited are Noam Gottesman, Pierre Lagrange, Philippe Jabre and Lehman (Cayman) Limited, a subsidiary of Lehman Brothers Holdings, Inc., a publicly-held entity. The managing directors of GLG Partners Limited are Noam Gottesman, Pierre Lagrange and Emmanuel Roman, and as a result, each has voting and dispositive power over the securities held by the Funds. GLG Partners LP, GLG Partners Limited, Noam Gottesman, Pierre Lagrange and Emmanuel Roman disclaim beneficial ownership of the securities held by the Funds except for their pecuniary interest therein. (b) Percent of class: The Company's proxy statement on Form DEF 14A that was filed on December 28, 2005, indicates there were 21,550,612 shares of Common Stock outstanding as of December 15, 2005. Therefore, based on the Company's outstanding shares of Common Stock, (i) GLG North American Opportunity Fund may be deemed to beneficially own 5.78% of the outstanding shares of Common Stock of the Company, and (ii) GLG Partners LP, GLG Partners Limited, Noam Gottesman, Pierre Lagrange and Emmanuel Roman may be deemed to beneficially own 9.17% of the outstanding shares of Common Stock of the Company. The foregoing should not be construed in and of itself as an admission by any Reporting Person as to beneficial ownership of shares of Common Stock owned by another Reporting Person. (c) Number of shares as to which such person has: (i) Sole power to vote or to direct the vote 0 (ii) Shared power to vote or to direct the vote See Item 4(a) above. (iii) Sole power to dispose or to direct the disposition of 0 (iv) Shared power to dispose or to direct the disposition of See Item 4(a) above. Item 5. Ownership of Five Percent or Less of a Class If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following: [ ] Item 6. Ownership of More than Five Percent on Behalf of Another Person CUSIP No. 969199108 13G Page 11 of 13 Pages Not applicable. Item 7. Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company Not applicable. Item 8. Identification and Classification of Members of the Group See Exhibit I. Item 9. Notice of Dissolution of Group Not applicable. Item 10. Certification By signing below each of the undersigned certifies that, to the best of its knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect. Exhibits: Exhibit I: Joint Filing Agreement, dated as of January 26, 2006, by and among GLG North American Opportunity Fund, GLG Partners LP, GLG Partners Limited, Noam Gottesman, Pierre Lagrange and Emmanuel Roman. CUSIP No. 969199108 13G Page 12 of 13 Pages SIGNATURES After reasonable inquiry and to the best of its knowledge and belief, each of the undersigned certifies that the information with respect to it set forth in this statement is true, complete, and correct. Dated: January 26, 2006 GLG NORTH AMERICAN OPPORTUNITY FUND By: GLG Partners LP, GLG PARTNERS LP as its Investment Manager By: GLG Partners Limited, By: GLG Partners Limited, as its General Partner as its General Partner /s/ Noam Gottesman /s/ Noam Gottesman ---------------------------- ---------------------------- Name: Noam Gottesman Name: Noam Gottesman Title: Managing Director Title: Managing Director /s/ Victoria Parry /s/ Victoria Parry ---------------------------- ---------------------------- Name: Victoria Parry Name: Victoria Parry Title: Senior Legal Counsel Title: Senior Legal Counsel GLG PARTNERS LIMITED NOAM GOTTESMAN /s/ Noam Gottesman /s/ Noam Gottesman ---------------------------- ---------------------------- Name: Noam Gottesman Title: Managing Director /s/ Victoria Parry ---------------------------- Name: Victoria Parry Title: Senior Legal Counsel PIERRE LAGRANGE /s/ Pierre Lagrange ---------------------------- ---------------------------- EMMANUEL ROMAN /s/ Emmanuel Roman ---------------------------- CUSIP No. 969199108 13G Page 13 of 13 Pages EXHIBIT I JOINT FILING AGREEMENT This will confirm the agreement by and among the undersigned that the Schedule 13G filed with the Securities and Exchange Commission on or about the date hereof with respect to the beneficial ownership by the undersigned of the Common Stock, $0.05 par value, of Willbros Group, Inc., a Republic of Panama corporation, is being filed, and all amendments thereto will be filed, on behalf of each of the persons and entities named below in accordance with Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended. This Agreement may be executed in two or more counterparts, each of which shall be deemed an original, but all of which together shall constitute one and the same instrument. Dated as of January 26, 2006 GLG NORTH AMERICAN OPPORTUNITY FUND By: GLG Partners LP, GLG PARTNERS LP as its Investment Manager By: GLG Partners Limited, By: GLG Partners Limited, as its General Partner as its General Partner /s/ Noam Gottesman /s/ Noam Gottesman ---------------------------- ---------------------------- Name: Noam Gottesman Name: Noam Gottesman Title: Managing Director Title: Managing Director /s/ Victoria Parry /s/ Victoria Parry ---------------------------- ---------------------------- Name: Victoria Parry Name: Victoria Parry Title: Senior Legal Counsel Title: Senior Legal Counsel GLG PARTNERS LIMITED NOAM GOTTESMAN /s/ Noam Gottesman /s/ Noam Gottesman ---------------------------- ---------------------------- Name: Noam Gottesman Title: Managing Director /s/ Victoria Parry ---------------------------- Name: Victoria Parry Title: Senior Legal Counsel PIERRE LAGRANGE /s/ Pierre Lagrange ---------------------------- ---------------------------- EMMANUEL ROMAN /s/ Emmanuel Roman ----------------------------