The continuing aims of the Physician-Scientist Award Program described in this renewal application will at the same time meet our needs for investigators in leadership positions for our rapidly-developing Stein Institute for Research on .Aging, established on the campus of the University of California San Diego in 1983. The identification, recruitment, and training of the brightest and best M. D.'s into the arena of clinical investigation on subjects related to aging will also meet the objectives of the National Institute on Aging (NIA). Physicians in their early years of clinical training will be invited to apply for a five-year intensive training program that will equip them with the strong basic science orientation needed for truly productive research on biomedical problems. Emphasis in this proposal is placed on providing tracks that will prepare candidates to carry out research on problems relating to some six major body systems that are prone to deterioration in function and development of pathology with advancing years. The first two or three years of training will be at the most basic level so that the trainees can, it is hoped, attack frontier problems using frontier methods. During this phase of their training, the candidates will be assigned to faculty sponsors working in fundamental disciplines of broad applicability to biomedical problems. Direct laboratory research experience will be supplemented by didactic training designed to fill gaps in their basic science background as well as to make up for gaps in previous education related to gerontology and geriatric medicine. Thus, liberal use will be made of the rich menu of basic science courses offered on the La Jolla campus and this will be supplemented by a well-organized course in geriatrics/gerontology. The last two or three years of training will be devoted to research problems bearing on the pathophysiology of one of the six concentration areas of interest to NIA. The nucleus of UCSD faculty planning for this program is drawn from the Departments of Biology and Chemistry on the general campus, and the basic and clinical faculty of the School of Medicine. They have each been selected on the basis of their proven productivity in research and their track records in training programs. Included are four faculty honored by election to the National Academy of Sciences. All will have as their goal the development of these young investigators so that after five years they will be ready for full responsibility as junior faculty members with their own research support. Because of the remarkable success of this program and continuing requests for participation by well-qualified young clinicians, we are requesting support for 10 positions.