Ownership Submission
FORM 3
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
  HARRIS JEFFREY
2. Date of Event Requiring Statement (Month/Day/Year)
05/11/2011
3. Issuer Name and Ticker or Trading Symbol
Kosmos Energy Ltd. [KOS]
(Last)
(First)
(Middle)
C/O WARBURG PINCUS LLC, 450 LEXINGTON AVE
4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
__X__ Director _____ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
5. If Amendment, Date Original Filed(Month/Day/Year)
(Street)

NEW YORK, NY 10017
6. Individual or Joint/Group Filing(Check Applicable Line)
_X_ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Beneficially Owned
1.Title of Security
(Instr. 4)
2. Amount of Securities Beneficially Owned
(Instr. 4)
3. Ownership Form: Direct (D) or Indirect (I)
(Instr. 5)
4. Nature of Indirect Beneficial Ownership
(Instr. 5)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly. SEC 1473 (7-02)
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Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 4)
2. Date Exercisable and Expiration Date
(Month/Day/Year)
3. Title and Amount of Securities Underlying Derivative Security
(Instr. 4)
4. Conversion or Exercise Price of Derivative Security 5. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 5)
6. Nature of Indirect Beneficial Ownership
(Instr. 5)
Date Exercisable Expiration Date Title Amount or Number of Shares
Series A Convertible Preferred Units   (1)   (1) Common Shares 87,664,716 $ (1) I See Footnotes (2) (3)
Series B Convertible Preferred Units   (1)   (1) Common Shares 59,157,300 $ (1) I See Footnotes (2) (3)
Series C Convertible Preferred Units   (1)   (1) Common Shares 2,588,876 $ (1) I See Footnotes (2) (3)
C1 Units   (1)   (1) Common Shares 4,968,245 $ (1) I See Footnotes (2) (3)

Reporting Owners

Reporting Owner Name / Address Relationships
Director 10% Owner Officer Other
HARRIS JEFFREY
C/O WARBURG PINCUS LLC
450 LEXINGTON AVE
NEW YORK, NY 10017
  X      

Signatures

/s/ Jeffrey A. Harris 05/11/2011
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 5(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) The securities underlying the derivative securities reported herein are issuable pursuant to the corporate reorganization (the "Corporate Reorganization") that will be completed simultaneously with, or prior to, the closing (the "Closing") of the initial public offering of common shares, par value $0.01 (the "Common Shares") of Kosmos Energy Ltd. (the "Issuer") in exchange for the outstanding units of Kosmos Energy Holdings ("KEH"), which units are exchangeable pursuant to the Fourth Amended and Restated Operating Agreement of KEH upon the Closing based on the pre-offering equity value of such units.
(2) Pursuant to the Corporate Reorganization, Warbur Pincus Private Equity VIII, L.P., a Delaware limited partnership ("WPPE VIII," and together with two affiliated partnerships, "WP VIII"), and Warburg Pincus International Partners, L.P., a Delaware limited partnership ("WPIP LP," and together with two affiliated partnerships, "WPIP"), have the right to acquire as of the date of this filing 154,379,137 Common Shares of the Issuer in connection with the Closing, which is expected to occur on May 16, 2011.
(3) Warburg Pincus Partners, LLC, a New York limited liability company ("WP Partners") and direct subsidiary of Warburg Pincus & Co., a New York general partnership ("WP"), is the sole general partner of WPPE VIII and WPIP LP. WP is the managing member of WP Partners. WP VIII and WPIP are managed by Warburg Pincus LLC, a New York limited liability company ("WP LLC"). Charles R. Kaye and Joseph P. Landy are Managing General Partners of WP and Managing Members and Co-Presidents of WP LLC. Mr. Harris is a Partner of WP and a Managing Director and a Member of WP LLC. The Common Shares of the Issuer which WP VIII and WPIP have the right to acquire are reflected as indirectly beneficially owned by Mr. Harris because of his affiliation with the Warburg Pincus entities. Mr. Harris disclaims benefical ownership with respect to any Common Shares of the Issuer in which he does not have a direct pecuninary interest.

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