EXHIBIT 10.10(b)

SECOND AMENDMENT TO THE

CENTENE CORPORATION

2002 EMPLOYEE STOCK PURCHASE PLAN

This amendment to the Centene Corporation 2002 Employee Stock Purchase Plan (the “Plan”) was approved by the Centene Corporation Board of Directors and became effective on January 1, 2006. The Plan is hereby amended by:

1. Deleting Section 9 of the Plan in its entirety and replacing it with the following:

“9. Purchase of Shares. On the Offering Commencement Date of each Plan Period, the Company will grant to each eligible employee who is then a participant in the Plan an option (“Option”) to purchase on the last business day of such Plan Period (the “Exercise Date”), at the Option Price hereinafter provided for, the largest number of whole shares of Common Stock of the Company as does not exceed the number of shares determined by multiplying $2,083 by the number of full months in the Offering Period and dividing the result by the closing price (as defined below) on the Offering Commencement Date of such Plan Period.

Notwithstanding the above, no employee may be granted an Option (as defined in Section 9) that permits the employee’s rights to purchase Common Stock under this Plan and any other employee stock purchase plan (as defined in Section 423(b) of the Code) of the Company and its subsidiaries, to accrue at a rate that exceeds $25,000 of the fair market value of such Common Stock (determined at the Offering Commencement Date of the Plan Period) for each calendar year in which the Option is outstanding at any time.

The purchase price for each share purchased will be 95% of the closing price of the Common Stock on the Exercise Date. Such closing price shall be (a) the closing price on any national securities exchange on which the Common Stock is listed, (b) the closing price of the Common Stock on the Nasdaq National Market or (c) the average of the closing bid and asked prices in the over-the-counter-market, whichever is applicable, as published in The Wall Street Journal. If no sales of Common Stock were made on such a day, the price of the Common Stock for purposes of clauses (a) and (b) above shall be the reported price for the next preceding day on which sales were made.

Each employee who continues to be a participant in the Plan on the Exercise Date shall be deemed to have exercised the employee’s Option at the Option Price on such date and shall be deemed to have purchased from the Company the number of full shares of Common Stock reserved for the purpose of the Plan that the employee’s accumulated payroll deductions on such date will pay for, but not in excess of the maximum number determined in the manner set forth above.

Any balance remaining in an employee’s payroll deduction account at the end of a Plan Period will be automatically refunded to the employee, except that any balance that is less than the purchase price of one share of Common Stock will be carried forward into the employee’s payroll deduction account for the following Offering, unless the employee elects not to participate in the following Offering under the Plan, in which case the balance in the employee’s account shall be refunded.”