- M. Caldwell Butler Papers
1945-200652
- M. Rosaria Piomelli Architectural Collection, 1960/19953
- M. Thomas Inge papers, 1879/20018
- Mabel Harris Papers, 1888-19456
- Maggie Anderson, Poet, Papers, 1958/2017, bulk 1980/201211
- Major William Henry Johnson Papers
1884-1935344
- Malcolm Bell Papers1
- Manuscripts - Geographic Names, Business Names and Subjects, 1725/194945
- Manuscripts Artifact Collection, 1800/2010194
- Manuscripts Audiovisual Collection, 1920/2013132
- Map Collection, 1629/19911
- Marc Harshman, Poet Laureate of West Virginia, Papers, 1970/202311
- Marcia Feuerstein Architectural Collection, 1982/199610
- Marcia de Garmo Loudoun County Development Collection, 1933-2008, n.d.14
- Margaret (Peggy) Cochrane Architectural Collection, 1951/19907