The Texas Medication Algorithm Project is a program designed to improve the quality of care of persons with serious mental disorders across sites in the Texas public mental health system and to create a uniform clinical environment from which cost estimates can be made. This paper describes the process of developing a pharmacological treatment algorithm for schizophrenia that addresses use of antipsychotics as well as other medications for side effects and co-existing symptoms. Input from clinicians, consultants, and consumers informed development of the algorithm, which was based on existing expert consensus guidelines. Information about the project can be found on the Internet at www.mhmr.state.tx.us/meds/tmap.htm. The authors present and describe the original and current versions of the algorithm, outline the feedback process by which it will be refined, and discuss how new medications will be incorporated as they enter the market.