- Adams Papers, 1782/18901
- Addie Rogers Bound Sheet Music Collection, 1827/18601
- Administration records collection, 1776/19761
- Advisory Committee Research Collection, 1772/20171
- Aileen Shafer, Collector, Material regarding African-Americans, 1829/18841
- Alabama Collection, 1823/18931
- Albert Frederick Wilson papers, 1840/19341
- Alderman family papers, 1779/19611
- Alexander Brown Papers (I), 1815/19101
- Alexander Brown Papers (II), 1748/19001
- Alexander Haight family collection, 1764/19761
- Alexander Hugh Holmes Stuart Account Books, 1837/18571
- Alexander McNutt Glasgow Family Papers, 1823/19031
- Alexander, Fultz, and Willson Families Collection, 1770/19701
- Alexandria Gazette Ledgers (MS026), 1833/18661