<PAGE>
                                                                    EXHIBIT 10.4

                         EXECUTIVE EMPLOYMENT AGREEMENT

         THIS AGREEMENT, made and entered into as of the 26th day of October,
2001 by and between CENTENE CORPORATION, a Wisconsin corporation (hereinafter
called the "Company"), and Mary O'Hara (hereinafter called the "Executive").

         1. EMPLOYMENT. Company hereby employs Executive as Executive Senior
Vice President of the Operations Group with such other or additional titles or
positions as Company's President, Vice Presidents, or Board of Directors may,
from time to time, determine.

         2. DUTIES. During the employment period, Executive shall faithfully
perform her duties to the best of her ability and in accordance with the
directions and orders (and to the satisfaction) of the Company's President, Vice
Presidents, and Board of Directors of Company, and she shall devote her full
working time, attention and energy to the performance of her duties.

         In addition to the duties assigned to her by the Company's President
and/or Vice Presidents and/or Board of Directors of Company, Executive shall
perform such other duties as are commensurate with her position and
responsibilities, including without limitation, exercising her best judgment;
safeguarding and saving from waste the assets of Company; and following,
maintaining, and implementing the business plans, budgets, business procedures
and directives established and promulgated by Company, as modified or amended
from time to time.

         Except as otherwise provided herein, Executive shall not render
services, directly or indirectly, to any other person or organization without
her Supervisor's prior written consent and shall not engage in any activity that
would interfere significantly with the faithful performance of her duties
thereunder. Executive may perform minor services for which she does not receive
compensation, provided that the activity does not conflict with the provisions
of her duties, without written consent.

         3. COMPENSATION. As compensation for all services rendered by Executive
under this agreement, company shall pay to Executive, in accordance with its
then prevailing payroll practices, a salary at the annualized rate of Two
Hundred Forty Thousand Dollars ($240,000.00), less applicable payroll
deductions. This salary may be adjusted from time to time as directed by the
Executive's immediate supervisor or the Company's or Plan's President.

         4. OTHER EMPLOYMENT BENEFITS. During the Employment Period:

                  (a)      Company shall reimburse Executive monthly for actual,
                           reasonable, and necessary out-of-pocket expenses she
                           incurs on Company's business in compliance with
                           company policies and procedures.

                  (b)      Executive shall participate in such of Company's
                           Executive plans or fringe benefit arrangements as
                           provided for all Executives, subject to their terms
                           and conditions.



<PAGE>








                  (c)      Vacation Leave. During the Employment Term, Executive
                           shall be entitled to a number of vacation days as
                           established in the standard company policy for senior
                           executives. Executive shall accrue and receive full
                           compensation and benefits during her vacation leave
                           periods. Vacation leave shall be taken at such times
                           as do not have an adverse effect on the operations or
                           transactions of the Company or otherwise as Executive
                           and her immediate supervisor shall agree.

                  (d)      Bonus Plan. The annual target bonus is 30% of base
                           salary with potential to exceed that if and when the
                           company exceeds its Annual Operating Plan criteria.
                           This award is at the discretion of the Company's
                           President. The Bonus Plan may be adjusted from time
                           to time as directed by the Company's President.

         5. TERMINATION OF EMPLOYMENT.


                  (a)      Termination for Cause. If the Company terminates
                           Executive's employment For Cause, or if Executive
                           resigns from her employment pursuant to Subsection
                           5(b), Executive shall be entitled only to payment of
                           that portion of her Salary earned through and
                           including the Termination Date or the Resignation
                           Date at the rate of Salary in effect at that time.

                  (b)      Resignation. Executive may resign from her employment
                           with the Company at any time by providing written
                           notice of her resignation to her immediate supervisor
                           at least thirty (30) days before the Resignation
                           Date, in which case she shall be entitled to
                           compensation as provided in Subsection 5(a).

                  (c)      Death. If Executive dies during her employment, or
                           Executive is entitled to receive payments from the
                           Company pursuant to Section 5(a) at the time of her
                           death, Executive's estate or personal representative
                           shall be entitled to receive that portion of the
                           Salary, at the rate in effect at Executive's death,
                           that Executive earned through and including the date
                           of Executive's death.

                  (d)      Disability. If Executive becomes Permanently
                           Disabled, the Board may terminate Executive's
                           employment by providing written notice to Executive
                           at least 72 hours before the Termination Date. If
                           Executive resigns from employment with the Company as
                           a result of a Permanent Disability, or the Company
                           terminates Executive's employment as a result of a
                           Permanent Disability, Executive shall be entitled to
                           receive that portion of her Salary, at the rate in
                           effect at the time she became Permanently Disabled,
                           that she earned through and including the Termination
                           Date or Resignation Date, as applicable; provided,
                           however, the amount due and payable for the period on
                           and after the date on which Executive became
                           Permanently Disabled shall not be less than the
                           portion of the Salary that would have been paid to
                           her if she had continued in the




<PAGE>




                           Company's employment for the 180 day period following
                           the date on which she became Permanently Disabled.

                  (e)      Compensation Following Termination. If the Company
                           terminates Executive's employment other than For
                           Cause the Company shall pay Executive that portion of
                           her Salary earned through and including the
                           Termination Date or the Resignation Date at the rate
                           of Salary in effect at that time, plus an amount
                           equal to fifty two (52) weeks of her annualized
                           Salary paid as salary continuance in accordance with
                           the then current payroll practices, and conditioned
                           upon Executive's signing, and not revoking, a
                           complete Release of any and all claims. In such case,
                           Company shall pay for twelve (12) of the eighteen
                           (18) months health and dental insurance continuation
                           coverage to which Executive is entitled under the
                           Consolidated Omnibus Budget Reconciliation Act of
                           1985, Public Law 99-272, Title X (COBRA).

                  (f)      Change of Control In the event of a "Change in
                           Control" which, within 24 months from and after such
                           Change in Control results in (a) the involuntary
                           termination of Executive's employment by the Company,
                           or (b) the voluntary resignation of employment by
                           Executive because of (i) the reduction of Executive's
                           compensation, (ii) a material adverse change in
                           Executive's position with the Company or the nature
                           or scope of Executive's duties or (iii) a request by
                           the Company or the surviving entity of the
                           transaction that resulted in the Change of Control
                           that Executive relocate outside of the Metropolitan
                           St. Louis area which Executive refuses, then
                           Executive shall receive severance equal to (52) weeks
                           pay paid at her choice (which choice shall be
                           irrevocably made and set forth as part of the Release
                           described below) either as a lump sum payment or
                           salary continuance, rather than the severance paid
                           pursuant to paragraph 5(c) above, but conditioned
                           upon Executive's signing, and not revoking, a
                           complete Release of any and all claims. In such case,
                           Company shall pay for (12) of the eighteen (18)
                           months health and dental insurance continuation
                           coverage to which Executive is entitled under the
                           Consolidated Omnibus Budget Reconciliation Act of
                           1985, Public Law 99-272, Title X (COBRA). In
                           addition, the Company agrees to pay for reasonable
                           outplacement services arranged by the Company.
                           Notwithstanding the foregoing, no payment or payments
                           shall be made under this Agreement which would be an
                           "excess parachute payment" as defined in Section
                           280G(b) of the Internal Revenue Code of 1986, as
                           amended. Payments which would be "excess parachute
                           payments" shall be proportionately reduced so that no
                           portion of any payment shall constitute
                           an "excess parachute payment." For purposes hereof a
                           "Change in Control" of the Company shall be deemed to
                           occur if (i) any "person" (as such term is used in
                           Section Section 13(d) and 14(d) of the Securities
                           Exchange Act of 1934, as amended (the "Exchange
                           Act")), other than (A) persons who, at the date of
                           this Agreement, are the beneficial owners of 25% or
                           more of the Company's voting securities or (B) a
                           group including Executive, is or

<PAGE>




                           becomes the "beneficial owner" (as defined in Rule
                           13d-3 under the Exchange Act), directly or
                           indirectly, of securities of the Company representing
                           fifty percent (50%) or more of the combined voting
                           power of the Company's then outstanding securities,
                           or (ii) the shareholders of the Company approve a
                           merger or consolidation of the Company with any other
                           corporation, other than a merger or consolidation
                           which would result in the voting securities of the
                           Company outstanding immediately prior thereto
                           continuing to represent (either by remaining
                           outstanding or by being converted into voting
                           securities of the surviving entity) at least fifty
                           percent (50%) of the combined voting power of the
                           voting securities of the Company or such surviving
                           entity outstanding immediately after such merger or
                           consolidation. Further, for purposes hereof, a
                           "Change in Control" also shall be deemed to occur if
                           individuals who, as the date hereof, constitute the
                           Board of Directors of the Company (the "Incumbent
                           Board) cease for any reason to constitute at least a
                           majority of the Board of Directors of the Company;
                           provided, however, that an individual becoming a
                           director subsequent to the date hereof whose
                           election, or nomination for election by the Company's
                           shareholders, was approved by at least a majority of
                           the directors then comprising the Incumbent Board
                           shall be included within the definition of Incumbent
                           Board, but excluding, for this purpose, any such
                           individual whose initial assumption of office occurs
                           as a result of either an actual election contest (or
                           such terms are used in Rule 14a-11 of Regulation 14A
                           promulgated under the Exchange Act) or other actual
                           or threatened solicitation of proxies or consents by
                           or on behalf of a person other than the Board.


         6. COVENANTS.


                  (a)      Non-competition by Executive. The Executive
                           acknowledges that the list of the Company's customers
                           and customer contacts as it may exist from time to
                           time are valuable, special, and unique assets of the
                           Company's business. During the period of twelve (12)
                           months immediately after the termination of
                           Executive's employment with the Company for any cause
                           whatsoever, Executive will not, either directly or
                           indirectly, either for Executive or for any other
                           person, firm, Company or corporation, call upon,
                           solicit, divert, or take away, or attempt to solicit,
                           divert or take away any of the Executives, customers,
                           prospective customers, or business, of the Company
                           upon whom Executive called, solicited, catered, or
                           became acquainted during Executive's employment with
                           the Company.

                  (b)      Return of Company Records and Property. Executive
                           agrees that upon termination of Executive's
                           employment, for any cause whatsoever, Executive will
                           surrender to the Company in good condition all
                           property and equipment belonging to Company and all
                           records kept by Executive containing the names,
                           addresses or any other information with regard to

<PAGE>




                           customers or customer contacts of the Company, or
                           concerning any operational, financial or other
                           documents given to Executive during Executive's
                           employment with Company.

                  (c)      Non-disclosure by Executive. The Executive
                           acknowledges and agrees that any information obtained
                           by Executive while employed by the Company, including
                           but not limited to customer lists and customer
                           contacts, financial, promotional, marketing, training
                           or operational information, and employment data is
                           highly confidential, and is important to the Company
                           and to the effective operation of the Company's
                           business. Executive, therefore, agrees that while
                           employed by the Company, and at any time thereafter,
                           Executive will make no disclosure of any kind,
                           directly or indirectly, concerning any such
                           confidential matters relating to the Company or any
                           of its activities.

                  (d)      Enforcement. In the event of a breach or threatened
                           breach by the Executive of the provisions of this
                           Agreement, the Company shall be entitled to a
                           restraining order and/or an injunction restraining
                           the Executive from contacting, servicing or
                           soliciting Company's customers, or customer contacts,
                           or utilizing or disclosing, in whole or in part, the
                           list of the Company's customers, customer contacts,
                           employees, or financial, operational, promotional,
                           marketing, or training information, or from rendering
                           any services to any persons, firm, corporation,
                           association, or other entity to whom such list or
                           information, in whole or in part, has been disclosed
                           or is threatened to be disclosed. In the event the
                           Company is successful in any suit or proceeding
                           brought or instituted by the Company to enforce any
                           of the provisions of this agreement on account of any
                           damages sustained by the Company by reason of the
                           violation by the Executive of any of the terms and/or
                           provisions of this agreement to be performed by the
                           Executive, the Executive agrees to pay the Company
                           reasonable attorney's fees to be fixed by the Court.



<PAGE>








         7. INVENTIONS.


                  (a)      Executive shall promptly communicate and disclose in
                           writing to Company all those inventions and
                           developments including software, whether patentable
                           or not, as well as patents and patent applications
                           (hereinafter collectively called "Inventions"), made,
                           conceived, developed, or purchased by her, or under
                           which she acquires the right to grant licenses or to
                           become licensed, alone or jointly with others, which
                           have arisen or jointly with others, which have arisen
                           or may arise out of her employment, or relate to any
                           matters pertaining to, or useful in connection
                           therewith, the business or affairs of Company or any
                           of its subsidiaries. Included herein as if developed
                           during the employment period is any specialized
                           equipment and software developed for use in the
                           business of Company. All of Executive's right, title
                           and interest in, to, and under all such inventions,
                           licenses, and right to grant licenses shall be the
                           sole property of Company. Any such inventions
                           disclosed to anyone by Executive within one (1) year
                           after the termination of employment for any cause
                           whatsoever shall be deemed to have been made or
                           conceived by Executive during the Employment Period.

                  (b)      As to all such invention, Executive shall, upon
                           request of Company:

                           i.       Execute all documents which Company shall
                                    deem necessary or proper to enable it to
                                    establish title to such inventions or other
                                    rights, and to enable it to file and
                                    prosecute applications for letters patent of
                                    the United States and any foreign country;
                                    and

                           ii.      Do all things (including the giving of
                                    evidence in suits and other proceedings)
                                    which Company shall deem necessary or proper
                                    to obtain, maintain, or assert patents for
                                    any and all such inventions or to assert its
                                    rights in any inventions not patented.

         8. LITIGATION. Executive agrees that during her employment or
thereafter, she shall do all things, including the giving of evidence in suits
and other proceedings, which Company shall deem necessary or proper to obtain,
maintain or assert rights accruing to Company during the employment period and
in connection with which Executive has knowledge, information or expertise. All
reasonable expenses incurred by Executive in fulfilling the duties set forth in
this paragraph 8 shall be reimbursed by Company to the full extent legally
appropriate, including, without limitation, a reasonable payment for Executive's
time.

         9. MODIFICATION. No modification, amendment, or waiver of any of the
provisions of this Agreement shall be effective unless made in writing
specifically referring to this Agreement and signed by all parties therefore.

         10. ENTIRE AGREEMENT. This instrument constitutes the entire agreement
of the parties hereto with respect to Executive's employment and her
compensation therefore.


<PAGE>





         11. WAIVER. The failure to enforce at any time any of the provisions of
this agreement or to require at any time performance by any party of any of the
provisions hereof shall in no way be construed to be a waiver of such provisions
or to affect either the validity of this Agreement, or any part hereof, or the
right of each party thereafter to enforce each and every provision in accordance
with the terms of this Agreement.

         12. SEVERABILITY. The invalidity or unenforceability of any particular
provision of this Agreement shall not affect the other provisions hereof, and
this Agreement shall be construed in all respects as if such invalid or
unenforceable provision were omitted.

         13. PRONOUNS. As used herein, the term "Executive" and the pronouns
therefore have been used for convenience only, and corresponding terms
reflecting the proper gender of Executive shall be deemed substituted by the
parties hereto where appropriate.

         14. SUCCESSORS. This Agreement shall be binding upon and shall inure to
the benefit of Company and any successor or assign of Company. For the purposes
of this Agreement, the terms "successor or assign" shall mean any person, firm,
corporation, or other business entity which, at any time, whether by merger,
purchase, assignment or otherwise, shall acquire the assets or business of
Company in part or as a whole.

         This Agreement shall also be binding upon and shall inure to the
benefit of Executive and her legal representatives and assigns, except that
Executive's obligations to perform such future services and rights to receive
payment therefore are hereby expressly declared to be non-assignable and
non-transferable.

         15. GOVERNING LAW. This Agreement shall be interpreted and executed in
accordance with the laws of the State of Missouri.

         IN WITNESS WHEREOF, the parties hereto have caused this instrument to
be duly executed as of the day and year first above written.

                                CENTENE CORPORATION


                                By  /s/ Michael F. Neidorff
                                  ----------------------------------------------
                                         "Company"



                                By /s/ Mary O'Hara
                                  ----------------------------------------------
                                         "Executive"



Date October 26, 2001
    -----------------------