This article discusses outcome evaluation systems for mental health programs. It reviews and critically evaluates design and analysis methods for strengthening the validity of such uncontrolled comparisons. The article examines methods for statistically adjusting preexisting groups, now referred to as risk adjustment or case-mix adjustment, and offers guidelines for determining when this procedure is appropriate. Then, analyses on two dependent variables--a global rating of functioning and a consumer satisfaction measure--available from an outcomes evaluation system currently underway in Florida are used to demonstrate the proposed method of risk adjustment. Results for 24 providers of mental health services showed that while risk adjustment only made a small difference in the overall provider rankings, the ranking of some specific providers changed considerably. The article concludes with a discussion of the implications of this research.