OBJECTIVES: The mission of the VA HSR&D Center for Health Care Evaluation is to conduct, disseminate, and provide training in health services research that results in more effective and cost-effective care for veterans and for the nation's population as a whole. The Center is composed of core and affiliated groups of professional health services researchers. It has an Advisory Committee and an HSR&D Subcommittee that is a Subcommittee of the VA Palo Alto Health Care System's (PA HCS) R&D Committee, that is responsible for reviewing health services research proposals. Members of the Advisory Committee provide direct linkage to the Sierra Pacific Network Administration, PA HCS's Director's Office, various clinical services, the other participating VA facilities, and Stanford University, the primary supporting institution. RESEARCH PLAN: The Center's health services research tries to understand the processes that link health care system and patient factors to treatment outcomes. The general framework that guides the Center's work describes the health care system in terms of physical features, organizational structure and policies, casemix, and types of health care tasks. These system factors influence patients who enter the system; in turn, health care system and patient characteristics affect the selection and allocation of services and the implementation and process of care. System factors also affect the work environment and staff morale and performance. In turn, each of these sets of factors influence health care outcomes. METHODOLOGY: Guided by this overall conceptual model of effective health care, the Center is pursuing a series of projects that involve (1) the organization and delivery of services, (2) decision aids, screening, and clinical decision making, (3) substance abuse and psychiatric disorders and their treatment, and (4) health services research methodology. FINDINGS AND CLINICAL RELEVANCE: The Center's work on the organization and delivery of services is helping the VA fulfill its mission to provide quality care to eligible veterans in all parts of the United States. Research on treatment selection processes, diagnostic assessment and screening, and clinical decision making is producing results to help bring patients who are in need of treatment into the health care system and to enhance the efficiency of identifying and treating specific disorders. Work in the areas of substance abuse and psychiatric treatment is improving the process, continuity, and outcome of care for these disorders. In addition to examining patient prognostic indicators and the outcome of care, these findings focus on treatment, psychosocial, and patient-treatment matching processes in order to improve mental health services to VA patients.