- A. H. Hand Papers, 1835/20091
- A. K. Leake Papers, 1872/19401
- Albert C. Swindler Papers, 1862/1929, bulk 1862/18641
- Alexander Brown Papers (I), 1815/19101
- Alexander Hamilton, Jr. Letters, 1832/18331
- Alfred E. Bradley Papers, 1864/1922, bulk 1916/19181
- Allen-Kean-Laurence family letters, 1837/19601
- Alumni Association Records, 1833/2014, bulk 1950/20051
- Alvin Duke Chandler Papers, 1896/1984, bulk 1950/19601
- Amos Koontz Papers I, 1809/1965, bulk 1936/19651
- Amos Koontz Papers II, 1865/19701
- Anatole and Vladimir Kalichevsky Papers, 1871/19551
- Anne T. Chapman Papers, 1884/19541
- Anson Du Puy Van Buren letters, 1863/19971
- Armistead-Cocke Papers, 1680/19171