- A. Jane Duncombe Architectural Papers, 1952/20021
- A. L. McLeod Papers, 1964/19661
- A. Patrick L. Prest, Jr. papers, 1941/20141
- A. Rufus Tonelson Papers, 1922/19751
- A. Willis Robertson Papers, 1921/1988, bulk 1946/19661
- A.B. Sharp, Compiler, Barr Family Genealogy, 1960/19691
- A.J. Morrison Collection, 1754/19751
- Abbye A. Gorin Architectural Collection, 1940/2006, bulk 1995/20061
- Abraham Anson papers, 1939/20052
- Ada Haldeman Ford, Suffragist, Papers, 1900/19701
- Adagio Press Collection, 1957/19931
- Adalbert J. Volck Collection of Etchings, 1861/19791
- Adam Empie Papers, 1811/2004, bulk 1811/18501
- Addison H. Smith papers, 1917/1970, bulk 1917/19221
- Adele Blow Chatfield-Taylor family papers, 1899/19771