A
- Access Board
- Administration for Children and Families (ACF)
- Administration for Native Americans
- Administration on Aging (AoA)
- Administration on Developmental Disabilities
- Administrative Committee of the Federal Register
- Administrative Conference of the United States
- Administrative Office of the U.S. Courts
- Advisory Council on Historic Preservation
- African Development Foundation
- Agency for Healthcare Research and Quality (AHRQ)
- Agency for International Development
- Agency for Toxic Substances and Disease Registry
- Agricultural Marketing Service
- Agricultural Research Service
- Agriculture Department
- Air and Radiation Hotline
- Air Force
- Alcohol and Tobacco Tax and Trade Bureau (Treasury)
- Alcohol, Tobacco, Firearms, and Explosives Bureau (Justice)
- American Battle Monuments Commission
- AmeriCorps Recruiting
- AMTRAK (National Railroad Passenger Corporation)
- Animal and Plant Health Inspection Service
- Antitrust Division
- Appalachian Regional Commission
- Architect of the Capitol
- Archives (National Archives and Records Administration)
- Arctic Research Commission
- Armed Forces Retirement Home
- Arms Control and International Security
- Army
- Army Corps of Engineers
- Arthritis and Musculoskeletal Interagency Coordinating Committee
- Atlantic Fleet Forces Command
