Collection
- Josephine Dyer Varnum and John P. Varnum correspondence, 1872-18882
- Kate M. Young papers, 1860-18702
- Katherine S. Minor collection, 1859-18692
- L. A. Brown notebook and logbook, 1868-18692
- Latin America collection, 1518-1883 (majority within [18th-19th century])57
- Leo Engleman cypher book, 1847-18482
- Letters, Documents, & Other Manuscripts, Duane Norman Diedrich collection, 1595-2007 (majority within 1719-1945)817
- Letters, Documents, & Other Manuscripts, E. L. Diedrich Collection, 1789-1987 (majority within 1795-1941)58
- Letters, Documents, & Sermons, Blandina Diedrich collection, 1652-1967 (majority within 1726-1886)291
- Lewis Cass papers, 1774-192423
- Liberty Bell Tour Photograph Album, 19152
- Lindley Fisher correspondence, 1846-1851 (majority within 1846-1849)3
- Louisiana Purchase Exposition Photograph Album, 19042
- Lucius Lyon papers, 1770-1934 (majority within 1833-1851)123
- Lukens-Parry family carte de visite album, ca. 1860s-19502
- Lydia Maria Child papers, 1835-189494
- Magdalena Nees notebooks, [ca. 1912]2
- Magdalene Minsing penmanship book, [circa 1870s]2
- Mamie P. Schultz notebook, 18912
- Manuscript Recipe Book collection, 1793-1959 (majority within 19th century)32