- McBee Sons & Company Store Ledger Book, 1846-1861508
- McLeod Family Papers, 1873-1990 (bulk 1900-1965)3
- Medical Society of South Carolina Collection1
- Medical Society of South Carolina Digital Collections80
- Micajah Adolphus Clark Journals, 1847-18572
- Middleton Family Papers, 1736-19291
- Middleton Papers, 1775-18158
- Midlands Memories1
- Millbrook account, n.d.1
- Millicent E. Brown Papers, 1949 - 20034
- Mills Family of Greenville114
- Miriam DeCosta Seabrook and Herbert U. Seabrook Papers, 1882-19952
- Modjeska Simkins Papers, 1909-1992155
- Modjeska Simkins: In Her Own Words23
- Mrs. William Timmons Receipt Book, 183138
- Mulberry Plantation Journals, 1853-1908 (bulk 1853-1889)295
- Muster Roll and Orders to the Commissary, 1772-17818
- Nathaniel Russell Middleton Papers, 1823-18814
- Neves Family Letters66
- Newton Plantation Collection18