The Substance Abuse and Mental Health Services Administration is a branch of the U.S. Department of Health and Human Services. SAMHSA is charged with improving the quality and availability of treatment and rehabilitative services in order to reduce illness, death, disability, and the cost to society resulting from substance abuse and mental illnesses. The Administrator of SAMHSA reports directly to the Secretary of the U.S. Department of Health and Human Services. SAMHSA's headquarters building is located outside of Rockville, Maryland.

The National Institute on Drug Abuse (NIDA) is a United States federal government research institute whose mission is to "advance science on the causes and consequences of drug use and addiction and to apply that knowledge to improve individual and public health."