Increasingly, people receiving public-supported health care are seeking help for and/or presenting with both substance abuse and mental disorders. People with these co-occurring disorders often require help from many different care systems. Consequently, no single system of care is adequately prepared to help people with both mental and substance abuse disorders on its own, and many people with co-occurring disorders do not receive the continuum of specialized services they need. This project seeks to identify strategies of developing effective treatment programs for people with co-occurring disorders. A national screening of the mental health and substance abuse fields identified programs in diverse settings that deliver effective treatment for different types of people with co-occurring disorders. Project participants discussed community-based programs and evaluated systemic support at the State, county, and regional levels. Systems-level participants described their strategies to build more comprehensive services. Throughout the process, participants described a wide range of clinical, financial, programmatic, and training barriers to delivering treatment and building systems of care. However, none of these obstacles are insurmountable; indeed, with consistency and clarity, participants described how they overcame each one. Their approaches included: using replicable strategies and tools; employing strong leadership at both the provider and systems levels; and involving important stakeholders. Finally, this report outlines a series of recommendations and"next steps." Seven appendixes include a Co-Occurring Disorders by Severity Matrix, findings from expert panels, and training curricula. (GCP)