In the United States, while the practice of medicine itself is regulated by the individual states, federal administrative agencies play a crucial role in the promulgation and implementation of national health policy, and the provision of health insurance and disability benefits. This chapter discusses the activities of these agencies and the limitations on them as imposed by administrative law. It provides a general overview of federal administrative law, and then a more detailed look at how these principles are applied (or differ) in the key federal health-related agencies, primarily the Department of Health and Human Services and its many important agencies such as the Food and Drug Administration, the Centers for Medicare and Medicaid Services, the Centers for Disease Control and Prevention, and the National Institutes of Health. It also covers the activities of the Social Security Administration and benefit programs in the Departments of Labor and Veterans Affairs.