Objective: This article selectively reviews evidence-based family and peer interventions for co-occurring mental illness and substance use disorders. Although few researchers have specifically investigated family interventions for dual disorders, considerable empirical evidence exists for the effectiveness of such interventions in treating each of the two disorders separately. Method: Quality of supporting research is examined and implications for dual disorders are explored. Results: Findings from multiple studies are that inclusion of families in treatment helps to engage treatment-resistant individuals, promotes treatment adherence and psychiatric stability, reduces relapse, reduces alcohol and illicit drug use, and improves well-being of clients and family members. Conclusions: Research and treatment implications are discussed with suggestions for integration of approaches derived from the two historically separate fields. (Contains 1 table.)