ABSTRACTBackground: Over seven million persons in the United States are supervised by the criminal justice system, including many who have co-occurring mental and substance use disorders (CODs). This population is at high risk for recidivism and presents numerous challenges to those working in the justice system. Objectives: To provide a contemporary review of the existing research and examine key issues and evidence-based treatment and supervision practices related to CODs in the justice system. Methods: We reviewed COD research involving offenders that has been conducted over the past 20 years and provide an analysis of key findings. Results: Several empirically supported frameworks are available to guide services for offenders who have CODs, including Integrated Dual Disorders Treatment (IDDT), the Risk-Need-Responsivity (RNR) model, and Cognitive-Behavioral Therapy (CBT). Evidence-based services include integrated assessment that addresses both sets of disorders and the risk for criminal recidivism. Although several evidence-based COD interventions have been implemented at different points in the justice system, there remains a significant gap in services for offenders who have CODs. Existing program models include Crisis Intervention Teams (CIT), day reporting centers, specialized community supervision teams, pre- and post-booking diversion programs, and treatment-based courts (e.g., drug courts, mental health courts, COD dockets). Jail-based COD treatment programs provide stabilization of acute symptoms, medication consultation, and triage to community services, while longer-term prison COD programs feature Modified Therapeutic Communities (MTCs). Conclusion: Despite the availability of multiple evidence-based interventions that have been implemented across diverse justice system settings, these services are not sufficiently used to address the scope of treatment and supervision needs among offenders with CODs.