Faced with high and increasing rates of mental disorder within the criminal justice system (CJS), a range of interventions have been implemented in an effort to prevent continued involvement in criminal activities among this population. A meta-analytic review was undertaken to consider the effectiveness of interventions for criminally involved adults with a mental disorder targeting either improved criminal justice or mental health outcomes. Furthermore, characteristics that were hypothesized to predict better outcomes were examined. Studies that considered sex offender interventions, or focused solely on antisocial personality, intellectual and cognitive, or substance use disorders were excluded. Results assuming a fixed-effects model combining 37 effect sizes from 25 studies (N = 15,678) support the effectiveness of these interventions in terms of reductions in any CJS involvement (d = 0.19 excluding one outlier). Interventions had no significant effect on an aggregate mental health outcome (d = 0.00). However, when considering distinct mental health outcomes, intervention participants had significantly better functioning (d = 0.20) and fewer symptoms (d = 0.12). There were no significant effects of the interventions on mental health service or medication use. Moderator analyses identified seven sample, intervention, and design characteristics that were related to the magnitude of the effect sizes for criminal justice outcomes, and suggest implications for service provision, policy, and research. Results suggested some relationship between intervention effects on mental health and criminal justice reinvolvement, although future research is needed in this area, especially given the absence of mental health outcome data in many studies.
