- 1x1 Japan Exhibition Materials, 1965-2024, 20242
- A. E. Dick Howard papers, 1928/201710
- A. H. Hand Papers, 1835/20091
- A. Jane Duncombe Architectural Papers, 1952/20021
- A. Patrick L. Prest, Jr. papers, 1941/201419
- A. Willis Robertson Papers, 1921/1988, bulk 1946/19661
- ALIVE (ALexandrians InVolved Ecumenically) Records (MS300), 1969/19957
- Abbye A. Gorin Architectural Collection, 1940/2006, bulk 1995/20061
- Abraham Anson papers, 1939/200544
- Adagio Press Collection, 1957/19934
- Adam Empie Papers, 1811/2004, bulk 1811/18501
- Admiral Thomas J. Lopez Papers, 1973/20147
- Advisory Committee Research Collection, 1772/201710
- African American Hugh Carr family, River View Farm, and the Papers of the Ivy Creek Foundation, 1916/19883
- Agnes Wolf papers, 1966/20061