Poor quality of care may contribute to impaired health status and excess mortality in individuals with serious mental disorders. However, little work has been done to design or test models for improving these patients' medical care in community mental health settings. The application seeks to develop and test a population-based medical case management model for improving general medical care for patients at an inner-city Community Mental Health Center in Atlanta, Georgia using a randomized, controlled study design. A total of 400 eligible individuals who agree to participate will be randomly assigned to medical case management or to usual care for two years. For subjects in the intervention group, a manualized, stepped-care care management intervention will provide patient education and activation, communication and advocacy with medical providers, and help in overcoming system-level barriers to primary care. The intervention draws on elements from the primary care, nursing case management, chronic disease, and health behavior change literature, and is based on study team's previous work in integrating primary care services for patients with serious mental illnesses. This proposed study will be the first randomized trial of an intervention to improve health and health care in a nonintegrated public mental health setting. The results will provide data on the feasibility and outcomes of medical care management for patients with serious mental illnesses in community mental health settings.