Medicine, with its focus on individual organic pathology and interventions, has become a powerful and pervasive force in the definition and treatment of aging. The resulting "biomedicalization of aging" socially constructs old age as a process of decremental physical decline and places aging under the domain and control of biomedicine. This paper examines the effects of medicalization on the scientific enterprise and development of the knowledge base in aging, the status and work of the professions, policy, and public perception.