Employee Stock Purchase Plan

EXPRESS SCRIPTS, INC.

EMPLOYEE STOCK PURCHASE PLAN

(As amended and restated Effective for the Offering Period Commencing January 1, 2006)



1. Purpose . The purpose of the Plan is to provide employees of the Company and its Designated Subsidiaries with an opportunity to purchase Common Stock of the Company through accumulated payroll deductions. It is the intention of the Company to have the Plan qualify as an "Employee Stock Purchase Plan" under Section 423 of the Internal Revenue Code of 1986, as amended. The provisions of the Plan shall, accordingly, be construed so as to extend and limit participation in a manner consistent with the requirement of that section of the Code.



2. Definitions .



a) "Board" shall mean the Board of Directors of the Company.



b) "Code" shall mean the Internal Revenue Code of 1986, as amended.



c) "Common Stock" shall mean the Class A Common Stock, par value $0.01, of the Company.



d) "Company" shall mean Express Scripts, Inc., a Delaware corporation, and, unless the context requires otherwise, any Designated Subsidiary.



e) "Compensation" shall mean all regular straight time gross earnings and commissions, exclusive of payments for overtime, shift premium, incentive payments, bonuses and other compensation, and without reduction for contributions to any 401(k) plan sponsored by the Company.



f) "Contributions" shall mean all amounts credited to the account of a participant pursuant to the Plan.



g) "Designated Subsidiary" shall mean any Subsidiary which has been designated by the Board from time to time in its sole discretion as eligible to participate in the Plan.



h) "Employee" shall mean any person who is an employee of the Company for tax purposes whose customary employment with the Company is at least twenty (20) hours per week and more than five (5) months in a calendar year. For purposes of the Plan, the employment relationship shall be treated as continuing intact while the individual is on short term disability or other leave of absence approved by the Company. Where the period of leave exceeds 90 days and the individual's right to reemployment is not guaranteed either by statute or by contract, the employment relationship shall be deemed to have terminated on the 91 st day of such leave.



i) "Enrollment Date" shall mean the first business day of each Participation Period.



j) "Exchange Act" shall mean the Securities Exchange Act of 1934, as amended.



k) "Offering Date" shall mean the first business day of each Offering Period of the Plan.



l) "Offering Period" shall mean a period of one (1) month commencing on the first day of each calendar month except as otherwise indicated by the Company.



m) "Participation Period" shall mean a period of three (3) months commencing on January 1, April 1, July 1 and September 1 of each year except as otherwise indicated by the Company.



n) "Plan" shall mean this Employee Stock Purchase Plan.



o) "Purchase Date" shall mean the last day of each Offering Period of the Plan.



p) "Subsidiary" shall mean a corporation, domestic or foreign, which not less than 50% of the voting shares are held by the Company or a Subsidiary, whether or not such corporation now exists or is hereafter organized or acquired by the Company or a Subsidiary.



3. Eligibility .



a) Any person who is an Employee of the Company as of the first Offering Date of a given Participation Period, who has continuously been an Employee for at least thirty-one (31) days, and who is not a "senior executive" of the Company, as such term may be defined from time to time by the Board (or any committee administering the Plan in accordance with Section 13 hereof), shall be eligible to participate in Offering Periods of such Participation Period under the Plan, subject to the requirements of Section 5(a) and the limitations imposed by Section 423(b) of the Code.

b) Any provisions of the Plan to the contrary notwithstanding, no Employee shall be granted an option under the Plan (i) if, immediately after the grant, such Employee (or any other person whose stock would be attributed to such an Employee pursuant to Section 424(d) of the Code) would own stock and/or hold outstanding options to purchase stock possessing five percent (5%) or more of the total combined voting power or value of all classes of stock of the Company or of any Subsidiary, or (ii) if such option would permit his or her rights to purchase stock under all employee stock purchase plans (described in Section 423 of the Code) of the Company and its Subsidiaries to accrue at a rate which exceeds twenty-five thousand dollars ($25,000) of fair market value of such stock (determined at the time such option is granted) for each calendar year in which such option is outstanding at any time.



4. Offering Periods . The Plan shall be implemented by a series of Offering Periods, each with a duration of one (1) month, with new Offering Periods commencing on the first day of each calendar month (or at such other time or times as may be determined by the Board of Directors). The Plan shall continue until terminated in accordance with Section 19 hereof. The Board shall have the power to change the duration and/or the frequency of the Offering Period with respect to future offerings without stockholder approval if such change is announced at least fifteen (15) days prior to the scheduled beginning of the first Offering Period to be affected.



The Offering Periods shall be grouped in to three (3) month Participation Periods commencing on or about January 1, April 1, July 1 and September 1 of each year (or at such other time or times as may be determined by the Board of Directors). Employees shall be allowed to make elections with respect to their participation in the Plan with respect to each Participation Period (subject to Section 5 and the other terms hereof).



5. Participation .



a) An eligible Employee may become a participant in the Plan by completing a subscription agreement (in such form and manner as may be approved by the Board or the committee administering the Plan) authorizing payroll deductions and filing it with the Company's payroll office at least five (5) business days prior to the applicable Enrollment Date. A subscription agreement in effect for a participant for a particular Participation Period will continue in effect for subsequent Participation Periods if the participant remains an eligible Employee and has not withdrawn the subscription agreement pursuant to Section 10.



b) Payroll deductions shall commence on the first payroll following the Enrollment Date and shall end on the last payroll paid in the Participation Period to which the subscription agreement is applicable, unless sooner terminated by the participant as provided in Section 10 hereof.



c) By enrolling in the Plan, each participant will be deemed to have authorized the establishment of a brokerage account in his or her name at a securities brokerage firm, which firm shall serve as custodial agent for the purpose of holding shares purchased under the Plan. The account will be governed by, and subject to, the terms and conditions of a written agreement with the firm approved by the Board or the committee administering the Plan, which agreement shall, among other things, reflect the restrictions contained in Section 21(c) and Section 21(d).



d) Subject to the limitations of Section 3 hereof and Section 423(b)(8) of the Code, all cash dividends, if any, paid with respect to shares of Common Stock purchased under the Plan and held in a participant's account established under Section 5(c) shall be automatically invested in shares of Common Stock purchased at One Hundred Percent (100%) of fair market value (as determined under Section 7(b)) on the next Purchase Date. All non-cash distributions on Common Stock purchased under the Plan and held in a participant's account established under Section 5(c) shall be paid to the participant as soon as practical.



6. Method of Payment of Contributions .



a) The participant shall elect to have payroll deductions made each pay period during the Participation Period in an amount not less than one percent (1%) and not more than ten percent (10%), in whole number percentage increments, of such participant's Compensation in each pay period. All payroll deductions made by a participant shall be credited to his or her account under the Plan. A participant may not make any additional payments into such account. Except as otherwise provided in this Section 6(a), all Employees granted options under the Plan shall have the same rights and privileges.



b) A participant may increase or decrease his or her payroll deductions by filing a new subscription agreement at any time during a Participation Period. The change may not become effective sooner than the next pay period after filing of the subscription agreement. The Board or the committee administering the Plan, at its discretion, may limit the number of participation rate changes during any Participation Period or Offering Period and may, in its discretion, require up to five (5) business days prior written notice.



c) A participant may discontinue his or her participation in the Plan as provided in Section 10 hereof.



d) Notwithstanding the foregoing, to the extent necessary to comply with Section 423(b)(8) of the Code and Section 6(a) hereof, a participant's payroll deductions may be decreased to zero percent (0%) at any time during the Participation Period. Payroll deductions shall recommence at the rate provided in such participant's subscription agreement at the beginning of the first Offering Period which is scheduled to end in the following calendar year, unless terminated by the participant as provided in Section 10 hereof.



e) At the time of each exercise of a ...