This manual is intended to help train case managers to work more effectively with persons who have mental illness and are (or have been) homeless. The approach stresses assertive outreach in the community setting to improve the client's life in the community as the best means to prevent rehospitalization. The manual's 10 units address the following topics: qualities needed in an assertive community outreach worker; the client population and the model of assertive community treatment; features of mental illness and substance use disorders; general health issues among homeless persons with severe mental illness; establishment of financial security through public entitlements; the therapeutic alliance in the client's own setting; the total treatment approach--team issues and activities; establishing community support linkages with collateral service providers; processing assertive outreach experiences; and the larger picture (creating cultural relevance, increasing one's knowledge base, and impacting public policy). A 41-item bibliography is included in an appendix. (DB)