This article describes the key features of a comprehensive housing program serving formerly homeless and at-risk adults with serious and persistent mental illness. The program combines intensive case management, integrated dual diagnosis treatment, and other clinical services with a range of housing options which are operated under the auspices of a single agency. For individuals with co-occurring substance use disorder, housing responses are guided by a four stage model of treatment and recovery. The authors offer a rationale for the continuum approach's relevance for high risk populations, especially those in poor urban settings where safety and harm reduction are a high priority (authors). [abstract]