ARTHUR J. GALLAGHER & CO. SENIOR MANAGEMENT INCENTIVE PLAN

Exhibit 10.2

ARTHUR J. GALLAGHER & CO.

SENIOR MANAGEMENT INCENTIVE PLAN

I. Purposes

The purposes of the Arthur J. Gallagher & Co. Senior Management Incentive Plan (the “Plan”) are to retain and motivate the officers of Arthur J. Gallagher & Co. (the “Company”) and its subsidiaries who have been designated by the Compensation Committee (the “Committee”) to participate in the Plan for a specified Performance Period by providing them with the opportunity to earn incentive payments based upon the extent to which specified performance goals have been achieved or exceeded for an applicable Performance Period. It is intended that all amounts payable to Participants who are “covered employees” within the meaning of Section 162(m) of the Code will constitute “qualified performance-based compensation” within the meaning of U.S. Treasury regulations promulgated thereunder, and the Plan and the terms of any awards hereunder shall be so interpreted and construed to the maximum extent possible.

II. Certain Definitions

“Board” shall mean the Board of Directors of the Company.

“Code” shall mean the Internal Revenue Code of 1986, as amended.

“Committee” shall mean the Compensation Committee of the Board or such other committee designated by the Board that satisfies any then applicable requirements of the New York Stock Exchange, or such other principal national stock exchange on which the common stock of the Company is then traded, to constitute a compensation committee, and which consists of two or more members of the Board, each of whom shall be an “outside director” within the meaning of Section 162(m) of the Code.

“Company” shall mean Arthur J. Gallagher & Co., a Delaware corporation, and any successor thereto.

“Determination Period” shall mean, with respect to any Performance Period, a period commencing on or before the first day of the Performance Period and ending not later than the earlier of (i) 90 days after the commencement of the Performance Period and (ii) the date on which twenty-five percent (25%) of the Performance Period has been completed. Any action required to be taken within a Determination Period may be taken at a later date if permissible under Section 162(m) of the Code or regulations promulgated thereunder, as they may be amended from time to time.

“Individual Award Opportunity” shall mean the potential of a Participant to receive an incentive payment based on the extent to which the applicable performance goals for a Performance Period shall have been satisfied. An Individual Award Opportunity may be expressed in U.S. dollars or pursuant to a formula that is consistent with the provisions of the Plan.

“Participant” shall mean an officer of the Company or any of its subsidiaries who is designated by the Company to participate in the Plan for a Performance Period, in accordance with Article III.

“Performance Period” shall mean any period commencing on or after January 1, 2010 for which performance goals are established pursuant to Article IV. A Performance Period may be coincident with one or more fiscal years of the Company or a portion of any fiscal year of the Company.

“Plan” shall mean the Arthur J. Gallagher & Co. Senior Management Incentive Plan, as set forth herein, as it may be amended from time to time.

III. Administration

3.1 General. The Plan shall be administered by the Committee, which shall have the full power and authority to interpret, construe and administer the Plan and any Individual Award Opportunity granted hereunder (including reconciling any inconsistencies, correcting any defaults and addressing any omissions). The Committee’s interpretation, construction and administration of the Plan and all its determinations hereunder shall be final, conclusive and binding on all persons for all purposes.

3.2 Powers and Responsibilities. The Committee shall have the following discretionary powers, rights and responsibilities in addition to those described in Section 3.1.

3.3 Delegation of Power. The Committee may delegate some or all of its power and authority hereunder to the President and Chief Executive Officer or other executive officer of the Company as the Committee deems appropriate; provided, however, that with respect to any person who is a “covered employee” within the meaning of Section 162(m) of the Code or who, in the Committee’s judgment, is likely to be a covered employee at any time during the applicable Performance Period, only the Committee shall be permitted to (i) designate such person to participate in the Plan for such Performance Period, (ii) establish performance goals and Individual Award Opportunities for such person, and (iii) certify the achievement of such performance goals.

IV. Performance Goals

4.1 Establishing Performance Goals. The Committee shall establish within the Determination Period of each Performance Period one or more objective performance goals for each Participant or for any group of Participants (or both), provided that the outcome of each goal is substantially uncertain at the time the Committee establishes such goal. Performance goals shall be based exclusively on one or more of the following objective corporate-wide or subsidiary, division, operating unit or individual measures, stated in either absolute terms or relative terms, such as rates of growth or improvement: (i) the attainment of a specified fair market value for shares of our common stock for a specified period of time, (ii) earnings per share, (iii) return to stockholders, (iv) return on assets, (v) return on equity, (vi) revenue, (vii) cash flow, (viii) operating expense reduction, (ix) return on investment, (x) return on capital, (xi) operating margin, (xii) net income, (xiii) earnings before interest, taxes, depreciation and/or amortization, (xiv) operating earnings, (xv) net cash provided by operations, and (xvi) strategic business criteria, consisting of one or more objectives such as (A) geographic business expansion goals, (B) cost targets, (C) customer satisfaction ratings, (D) reductions in errors and omissions, (E) reductions in lost business, (F) management of employment practices and employee benefits, (G) supervision of litigation, (H) satisfactory audit scores, (I) productivity, (J) efficiency, and (K) goals relating to acquisitions or divestitures, or any combination of the foregoing. With respect to Participants who are not “covered employees” within the meaning of Section 162(m) of the Code and who, in the Committee’s judgment, are not likely to be a covered employees at any time during the applicable Performance Period, the performance goals established for the Performance Period may consist of any objective corporate-wide or subsidiary, division, operating unit or individual measures, whether or not listed herein. Performance goals shall be subject to such other special rules and conditions as the Committee may establish at any time within the Determination Period.

4.2 Impact of Extraordinary Items or Changes in Accounting. The measures utilized in establishing performance goals under the Plan for any given Performance Period shall be determined in accordance with generally accepted accounting principles (“GAAP”) and in a manner consistent with the methods used in the Company’s audited consolidated financial statements, without regard to (i) extraordinary or other nonrecurring or unusual items, or restructuring or impairment charges, as determined by the Company’s independent public accountants in accordance with GAAP or (ii) changes in accounting, unless, in each case, the Committee decides otherwise within the Determination Period or as otherwise required under Section 162(m) of the Code.

V. Incentive Award Opportunities

5.1 Terms. At the time performance goals are established for a Performance Period, the Committee also shall establish an Individual Award Opportunity for each Participant or group of Participants, which shall be based on the achievement of one or more specified targets of performance goals. The targets shall be expressed in terms of an objective formula or standard which may, at the discretion of the Committee, be based upon the Participant’s annual base salary or a multiple thereof. In all cases the Committee shall have the sole and absolute discretion to reduce the amount of any payment under any Incentive Award Opportunity that would otherwise be made to any Participant or to decide that no payment shall be made. No Participant shall receive a payment under the Plan with respect to any fiscal year of the Company in excess of $3,000,000, which maximum amount shall be prorated with respect to Performance Periods that are less than one year in duration.

5.2 Incentive Payments. Payments under Incentive Award Opportunities shall be in cash or shares under a stock incentive plan maintained by the Company, as determined by the Committee, and shall be made at the time determined by the Committee after the end of the Performance Period for which the Incentive Awards are payable, except that no such payment shall be made unless and until the Committee, based to the extent applicable on the Company’s audited consolidated financial statements for such Performance Period (as prepared and reviewed by the Company’s independent public accountants), has certified in writing the extent to which the applicable performance goals for such Performance Period have been satisfied.

VI. General

6.1 Effective Date and Term of Plan. The Plan shall be submitted to the stockholders of the Company for approval at the 2010 annual meeting of stockholders and, if approved by the affirmative vote of a majority of the shares of common stock of the Company present in person or represented by proxy at such meeting, shall become effective for Performance Periods beginning on and after January 1, 2010. This Plan shall terminate as of December 31, 2014, unless terminated earlier by the Board. In the event that this Plan is not approved by the stockholders of the Company, this Plan shall be null and void.

6.2 Amendment or Termination of Plan. The Board may amend or terminate this Plan as it shall deem advisable, subject to any requirement of stockholder approval required by applicable law, rule or regulation, including Section 162(m) of the Code.

6.3 Non-Transferability of Awards. No award under the Plan shall be transferable other than by will, the laws of descent and distribution or pursuant to beneficiary designation procedures approved by the Company. Except to the extent permitted by the foregoing sentence, no award may be sold, transferred, assigned, pledged, hypothecated, encumbered or otherwise disposed of (whether by operation of law or otherwise) or be subject to execution, attachment or similar process. Upon any attempt to sell, transfer, assign, pledge, hypothecate, encumber or otherwise dispose of any such award, such award and all rights thereunder shall immediately become null and void.

6.4 Tax Withholding. The Company shall have the right to require, prior to the payment of any amount pursuant to an award made hereunder, payment by the Participant of any Federal, state, local or other taxes which may be required to be withheld or paid in connection with such award.

6.5 No Right of Participation or Employment. No person shall have any right to participate in this Plan. Neither this Plan nor any award made hereunder shall confer upon any person any right to continued employment by the Company, any subsidiary or any affiliate of the Company or affect in any manner the right of the Company, any subsidiary or any affiliate of the Company to terminate the employment of any person at any time without liability hereunder.

6.6 Designation of Beneficiary. If permitted by the Company, a Participant may file with the Committee a written designation of one or more persons as such Participant’s beneficiary or beneficiaries (both primary and contingent) in the event of the Participant’s death. Each beneficiary designation shall become effective only when filed in writing with the Committee during the Participant’s lifetime on a form prescribed by the Committee. The spouse of a married Participant domiciled in a community property jurisdiction shall join in any designation of a beneficiary other than such spouse. The filing with the Committee of a new beneficiary designation shall cancel all previously filed beneficiary designations. If a Participant fails to designate a beneficiary, or if all designated beneficiaries of a Participant predecease the Participant, then each outstanding award shall be payable to the Participant’s executor, administrator, legal representative or similar person.

6.7 Governing Law. This Plan and each award hereunder, and all determinations made and actions taken pursuant thereto, to the extent not otherwise governed by the Code or the laws of the United States, shall be governed by the laws of the State of Illinois and construed in accordance therewith without giving effect to principles of conflicts of laws.

6.8 Other Plans. Neither the adoption of the Plan nor the submission of the Plan to the Company’s stockholders for their approval shall be construed as limiting the power of the Board or the Committee to adopt such other incentive arrangements as it may otherwise deem appropriate.

6.9 Binding Effect. The Plan shall be binding upon the Company and its successors and assigns and the Participants and their beneficiaries, personal representatives and heirs. If the Company becomes a party to any merger, consolidation or reorganization, then the Plan shall remain in full force and effect as an obligation of the Company or its successors in interest, unless the Plan is amended or terminated pursuant to Section 6.2.