Clients with co-occurring substance use and mental health disorders are not well served in traditional health care systems where specialist services offer segregated interventions and the client is left to negotiate required treatment across both systems. In recent years, policy change guiding the treatment of dual diagnosis in the United States, United Kingdom, Australia and elsewhere has triggered the development of diverse models of treatment, each of which function at different points on a continuum from serial to fully integrated care. This paper outlines key models and provides examples, while considering their potential for appropriately addressing the needs of this client group. Consideration is given to the benefits of an interaction between stepped care and the chosen model, as a means of enhancing care efficiency while retaining the focus on positive outcomes.