Project Summary/Abstract This proposal for the competing continuation of the University of Pittsburgh Training Program in the epidemiology of aging, funded by the NIA since 1989, is focused on the “Epidemiology of Musculoskeletal Decline and Disability in Aging.” The training program will include 3 pre- doctoral and 2 post-doctoral positions in epidemiology. Our rich multidisciplinary training environment is customized to the background of each trainee to address novel approaches in aging research with an emphasis on cutting-edge biological and physiological methods for epidemiology, a core discipline for research and practice in public health. Our professional career development for strong communication and analytic methods, has resulted in trainees that are actively recruited to postdoctoral and faculty positions within other universities, the government, and health care. We will continue to train the next generation of research professionals in aging epidemiology through mentored, hands-on, diverse research experiences with well-funded leaders in the field, and formal courses. The new focus of our Aims includes: 1) To apply the biology of aging and longevity to study usual and accelerated age-related physiologic change with focus in Muscle, Body Composition, Mobility, and Disability; Osteoporosis and Osteoarthritis; and Falls and Fall Injuries, for the epidemiology of age-related functional decline; 2) To advance epidemiologic and quantitative statistical methods in aging studies with a foundation in traditional skills and emphasis on state-of-art techniques; and 3) To use a multidisciplinary and collaborative approach to epidemiology for specialty areas of Biology of Aging and Longevity, Health Services, and Diversity, Health Equity and Social Determinants, in defining targets for active life expectancy and prevention of disability from mid- to late life. To develop trainee skills to lead investigator-initiated studies, we will create a Recruitment and Measurement Core. We have several new cohort studies in the field including the Study of Muscle, Mobility and Aging (SOMMA), a prospective, longitudinal cohort of older men and women to obtain muscle tissue samples, biomarkers and advanced imaging of muscle related to risk of mobility disability and another study to relate to these muscle phenotypes with bone parameters from high resolution peripheral quantitative computed tomography. We are a field site for TAME, a new randomized trial of metformin for reducing age-related multi-morbidity and functional decline. Our training program is uniquely poised to use our existing and new research in clinical trials and longitudinal cohort studies of aging to elucidate pathways of musculoskeletal health and physical function, with the goal of preventing disability in the aging population.