Osteoarthritis is the most common rheumatic illness in man and affects more than 40 million Americans. It causes major morbidity and disability, particularly, among the elderly. Current treatment for osteoarthritis is, however, fundamentally palliative. Thus, development of strategies to prevent osteoarthritis is critical. No published incidence studies exist that prospectively evaluate the risk of osteoarthritis in African- Americans. Further, the risk of excess weight and the role of physical activity in developing osteoarthritis is incompletely understood, and has not been studied longitudinally in younger individuals nor in Afro- Americans. Our primary goal is to identify the incidence of and risk factors for osteoarthritic in complementary prospective cohorts of black and white Americans. The fist cohort to be investigated is the Meharry-Hopkins Study, comprised of 592 former white medical students of the Johns Hopkins University School of Medicine (Classes of 1957-1964) and 435 black students at Meharry Medical College (Classes 1958-1965). The complementary cohort is the National Health and Nutrition Examination Survey-I Epidemiologic Follow-up Study, the only nationally representative longitudinal cohort of musculoskeletal disease, consisting of 6,913 adult Americans, aged 25-74 years, followed prospectively over a 10 year period. We propose to examine black-white differences in osteoarthritis incidence and risk factors, and to test hypotheses that excessive weight and higher levels of physical activity, measured early in adulthood, increase the risk of developing osteoarthritis in weight-bearing joints. These hypotheses will be tested by achieving the following aims: 1-To determine the cumulative incidence of osteoarthritis in a prospective cohort of black and white former medical students; 2-To determine the risk, in weight-bearing joints, of osteoarthritis associated with body weight and level of physical activity; 3-To perform a black-white comparison in the general population of the morbidity and mortality associated with knee and hip osteoarthritis; and 4-To determine the impact of changes in weight and physical activity, in persons with and without radiographic osteoarthritis at baseline. Further, identification of factors present at a young age, that increase the risk of osteoarthritis later in life, lays the necessary groundwork for the development of appropriate intervention programs. The candidate, a second-year rheumatology fellow at Johns Hopkins, is currently strengthening his knowledge in epidemiology and biostatistics in a full-time university degree program. In combining these critical methodologic tools, the invaluable mentorship of Drs. Wigley, Klag, and Hochberg, collectively outstanding epidemiologists and rheumatologists, and the practical experience in the pursuit of the aims of this proposal, Dr. Gelber will track toward an independent research career in clinical investigation.