Mental health courts have recently emerged with goals to reduce recidivism and improve clinical outcomes for people with serious mental illness in the criminal justice system. The present study is a review of mental health court literature assessing their effectiveness in reducing recidivism and improving clinical outcomes for participants using meta-analytic techniques. A total of 20 studies that included sufficient information to compute the standardized mean difference effect size, focused on adult populations, and were within the United States were included in the analysis. Only experimental and quasi-experimental research designs were obtained. Using Cohen's d (1988) guidelines, mental health courts were found to have a small effect on reducing recidivism (0.32, p<.05) and a nonsignificant effect for improving clinical outcomes for participants. Several moderator analyses were conducted and indicated that the nature of the control group (whether they were a treatment as usual or participants who "opted-out") was found to be significant between groups (Q=22.33, p<.001) as a possible moderating effect.