The delivery of services in a health maintenance organization (HMO) provides many opportunities for innovation. There is a growing awareness that many outpatient medical visits are related to psychological or social needs. Because of the economic incentive for HMO's to reduce inappropriate utilization, psychologists and psychotherapists will play a more influential role in health care delivery in the near future. Contributions can be made on all levels of prevention. For example, primary prevention could include community health education programs. Secondary prevention could bring together patients who are dealing with various life experiences and provide them with early interventions. Tertiary prevention could help patients to readjust by providing social support and by helping prevent relapses. (JAC)