Forensic mental health evaluation systems have undergone major changes during the past 20 years, and the variability of service delivery systems across States is significant. This study compared assessments of competence to stand trial and criminal responsibility in Michigan, Ohio, and Virginia. Although all three States used comparable legal criteria to judge competence and criminal responsibility, there were large, statistically significant differences among the States in the proportion of defendants referred for evaluation who were assessed as incompetent or not criminally responsible. In addition, there were significant differences in the diagnostic and offense categories of defendants referred for evaluation. Findings suggest that the structure of a system for providing forensic evaluation services may significantly affect both the group of individuals referred for evaluation and evaluation outcome. Tables, references