The Administration on Developmental Disabilities (ADD) is the U.S. Government organization responsible for implementation of the Developmental Disabilities Assistance and Bill of Rights Act of 2000, known as the DD Act. ADD, its staff and programs, are part of the Administration for Children and Families (ACF), of the U.S. Department of Health and Human Services(HHS).
For information on its Offices, Administrations, and Centers, take a look at the US Department of Health and Human Services Organizational Chart.