The primary objective of the study is to examine the incidence of physical disability in relation to body composition and weight-related health conditions in healthier older persons. Change in body composition in old age, particularly loss of muscle mass and bone, may be a common pathway by which multiple diseases contribute to risk of disability. The reasons for changes in weight and body composition in old age and the influence of these changes in health outcomes are not fully understood. The HEALTH ABC will include a total of 3,000 noninstitutionalized white and African- American men and women aged 70-79.