<PAGE>   1
                                                                   EXHIBIT 10.20

                                 ADDENDUM NO. 1

                        TENNESSEE BEHAVIORAL HEALTH, INC.
                               PROVIDER AGREEMENT

PAYOR PLAN:  The TennCare Partners Program

PLAN CONTRACT: Agreement for Behavioral Health Services to Enrollees under The
TennCare Partners Program between TBH and the Tennessee Department of Mental
Health and Mental Retardation.

EFFECTIVE DATE: This Addendum shall become effective as of the later of (i) the
date the Plan Contract between the State and TBH referenced above becomes
effective or (ii) the date this ADDENDUM NO. 1 is executed by the parties.

COVERED SERVICES: All services described in Attachment I.

PRIOR AUTHORIZATION REQUIREMENTS: All Designated Covered Services require Prior
Authorization with the exception of Emergency Care or care rendered by Providers
to their assigned enrollees at their discretion. Emergency Care is not subject
to Prior Authorization; however, Provider is required to give notice to TBH
within twenty-four (24) hours after the provision of Emergency Care or any
Referral for Emergency Care. Once the Enrollee has been stabilized, any
subsequent care is subject to Prior Authorization requirements.

ENROLLEE ASSIGNMENT: Each enrollee will be assigned to a provider by TBH.

COMPENSATION: TBH shall compensate Provider for providing
Medically/Psychologically Necessary Designated Covered Services to Enrollees of
the above-referenced plan as follows:

         As described in Attachment I.

COPAYMENT: In accordance with terms of Payor Plan.

WITHHOLDS: TBH reserves the right to institute withholds for any Participating
Provider failing to meet performance standards as outlined by TBH Policies, TBH
Procedures, TennCare, or any other regulatory or government body associated with
the administration of the TennCare Program.

ISSUE RESOLUTION: To the extent not specifically addressed by the terms of this
Addendum, all compensation issues shall be resolved in accordance with TBH
Policies and TBH Procedures.

SPECIAL TERMS, CONDITIONS OR OBLIGATIONS: The following terms, conditions,
covenant and obligations shall, apply to TBH or Provider, as appropriate,
notwithstanding any terms or conditions of the Agreement to the contrary.



                                     A1-1
<PAGE>   2

         1. DEFINITIONS. To the extent the Plan Contract contains definitions of
terms identical, similar or comparable to the terms defined in Article I of the
Agreement, the definition in the Plan Contract shall control the meaning of such
terms. References to the State shall mean the Tennessee Department of Mental
Health and Mental Retardation and, where appropriate, the Bureau of TennCare,
Tennessee Department of Finance and Administration and the Tennessee Department
of Commerce and Insurance. The term "MCO" refers to each managed care
organization that has entered into a Risk Agreement with the State for the
provision of certain health care services to TennCare enrollees.

         2. THIRD PARTY BENEFICIARY. Enrollees are the intended third party
beneficiary of the Plan Contract and this Agreement and, as such, are entitled
to remedies accorded to third party beneficiaries under the laws of the State.

         3. CASE MANAGEMENT. If Provider is designated as a Case Manager,
Provider shall not only perform the functions described in Article IV of the
Agreement, but will also assist and cooperate with State and TBH in performing
case management functions under the Plan Contract.

         4. LABORATORY TESTING. If Provider is to provide laboratory testing as
a Designated Covered Service, all laboratory testing sites utilized to provide
such services must have either a Clinical Laboratory Improvement Act (CLIA)
Certificate of Waiver or a Certificate of Registration along with a CLIA
identification number. Those laboratories with a Certificate of Waiver may
provide only the types of tests permitted under the terms of the waiver.

         5. COORDINATION OF BENEFITS. TBH shall be the Payor of last resort for
Designated Covered Services. TBH shall be entitled to full subrogation rights
and shall be responsible for determining the legal liability of third parties to
pay for Designated Covered Services and to recover any such amounts from the
third party. If TBH has determined that third party liability exists for part or
all of Designated Covered Services provided to an Enrollee, and the third party
will make payment to Provider in a reasonable time, TBH may pay Provider only
the amount, if any, by which the Provider's Clean Claim exceeds the amount of
third party liability, or TBH may pay the full amount due Provider under this
Agreement and assume full responsibility for collection from such third party.
TBH shall not withhold payment to Provider if third party liability or the
amount of liability cannot be determined or payment will not be made to Provider
within a reasonable time. Provider shall make such assignment and pay over such
amounts to TBH as shall be required by this paragraph or any applicable
provision of TBH Policies or TBH Procedures.

         6. PROVIDER WARRANTIES. Provider warrants that Provider has not been
excluded from participation in the Medicare or Medicaid programs pursuant to
Sections 1128 or 1156 of the Social Security Act and is in good standing with
TennCare.

         7. MAINTENANCE OF RECORDS. Medical health and behavioral records of
Enrollees and all related administrative records shall be maintained under
Section 2.12.2 of the Agreement for five (5) years after termination of the
Agreement and further if the records are under review or audit until the review
or audit is complete. Prior approval for the disposition of records must be
requested from the State.

         8. CLAIMS SUBMISSION. The time period for the submission of claims
under Section 2.19 of the Agreement shall bc no less than one hundred twenty
(120), and no more than one hundred eighty (180), calendar days from the date of
rendering services rather than (60) days. 


                                      A1-2
<PAGE>   3

         9. INDEMNIFICATION. At all times during the term of this Agreement,
Provider shall indemnify and hold harmless the State as well as its officers,
agents and employees (hereinafter the "Indemnified Parties") from all claims,
losses or suits incurred by or brought against the Indemnified Parties as a
result of failure of Provider to comply with the terms of this Agreement or the
Plan Contract.

         10. COMPLIANCE WITH LAWS. TBH and Provider agree to recognize and abide
by all State and federal laws, regulations and guidelines applicable to
TennCare, including The TennCare Partners Program, and the Plan Contract.

         11. INCORPORATION OF LEGAL OR CONTRACT REQUIREMENTS. The parties hereby
incorporate by reference all applicable federal and State laws or regulations
and agree that revisions of such laws or regulations shall automatically be
incorporated into this Addendum as they became effective. In the event the
changes in this Agreement or this Addendum as a result of revision in applicable
federal or State laws materially affect the position of either party, TBH and
Provider agree to negotiate such further amendments as may be necessary to
correct any inequities.

         12. SPECIAL TERMINATION PROVISIONS. In the event of a termination of
the Parties' obligations pursuant to Article VI with respect to this Addendum,
Provider shall immediately make available to the State, or its designated
representative, in usable form, any or all records, whether medical or
financial, related to the Provider's activities undertaken pursuant to this
Agreement with respect to this Addendum No. 1. Provision of such records shall
be at no expense to the State.

         13. OTHER CONTRACTS. Provider is required to accept compensation for
Designated Covered Services provided under this Agreement as set forth above,
but shall not be required to accept TennCare reimbursement amounts for services
to Enrollees who are covered under any other Plan Contract.

         14. QUALITY COMPLIANCE. In addition to all other requirements of this
Agreement, Provider must adhere to the quality of care monitors required by the
terms of the Plan Contract.

         15. ARBITRATION. The State shall have no involvement in arbitration
under Section 8.2 of the Agreement except to (i) enforce Section 8.2, (ii)
approve the arbitration procedure proposed by TBH and (iii) to voluntarily
intervene if the State deems intervention to be in the best interest of
TennCare; provided, however, that the State shall not be bound by said
arbitration. If at any time, the State decides that a particular dispute should
be in a court of competent jurisdiction, the State shall notify the parties to
the dispute of its decision to refer the dispute to a court of competent
jurisdiction and said arbitration process shall cease and the dispute shall be
heard in said court. The only exception to the arbitration process shall be
resolution of the cost of Emergency Care and providers of services under TENN.
CODE ANN. Section 33-2-601. The cost of establishing any arbitration procedure
shall be borne by TBH. If a dispute between the parties involving a claim
submitted by Provider to TBH is not resolved prior to entry of a final decision
by the arbitrator(s), then the prevailing party at the arbitration shall be
entitled to award of reasonable attorneys' fees and expenses from the
non-prevailing Party. Reasonable attorneys' fees means the number of hours
reasonably expended on the dispute multiplied by a reasonable hourly rate but
shall not exceed ten percent (10%) of the total monetary amount in dispute or
$500.00, whichever amount is greater.

         16. COORDINATION OF HEALTH CARE SERVICES. To the extent and in the
manner required by the terms of the Plan Contract, Provider will cooperate with
each MCO and the primary care providers under contract with or employed by such
MCO who provide medical services, to Enrollees in an effort to (i) coordinate
and integrate health care services provided to each Enrollee by such providers
and Provider, (ii) help ensure the appropriateness of all health care services
provided to the Enrollee and (iii) help ensure that such health care services
are. provided in a manner that allows the most efficient use of resources and
the achievement of quality health outcomes.



                                      A1-3
<PAGE>   4

         17. AMENDMENT TO ADDENDUM. Notwithstanding the provision of Article XII
to this Agreement, in the event this Agreement and Addendum No. 1 are executed
by the parties prior to execution of the Plan Contract, this Addendum No. 1
shall automatically be amended to conform to the requirements of the Plan
Contract and the State under The TennCare Partners Program. Any amendments
required after execution of the Plan Contract shall, be made in accordance with
the provisions of Article XIII of the Agreement. The terms of any amendment that
becomes effective by reason of the first sentence of this Paragraph shall be
provided to Provider by TBH within thirty (30) days after execution of the Plan
Contract by TBH and the State.

         18. ASSIGNMENT TO STATE. TBH shall have the right to assign to the
State its rights and delegate its duties and responsibilities under this
Agreement with respect to the Payor Plan and Plan Contract described in this
Addendum to the extent required by the terms of the Plan Contract.



                                      A1-4
<PAGE>   5

         IN WITNESS WHEREOF, the parties have executed this Addendum No. 1 in
multiple counterparts (including the use of counterpart signature pages if
necessary) as of the dates set forth below each party's signature.

                                  TBH:

                                  TENNESSEE BEHAVIROAL HEALTH, INC.



                                  By:  /s/ Rocky Davis
                                  ----------------------------------------------
                                  Title:  Chief Executive Officer
                                  Date:  December 4, 1995

                                  PROVIDER:

                                  IF AN ENTITY:

                                  /s/ Pam Womack, President
                                  ----------------------------------------------
                                  TENNESSEE MENTAL HEALTH COOPERATIVE



                                  By:
                                      ------------------------------------------

                                  Title:
                                         ---------------------------------------

                                  Date:  December 4, 1995

                                  IF AN INDIVIDUAL:


                                  ----------------------------------------------
                                               Type or Print Name


                                  ----------------------------------------------
                                              Type or Print Name



                                  Date:
                                        ----------------------------------------



                                      A1-5
<PAGE>   6

                               [EXHIBITS EXCLUDED]


                                      A1-6