Manuscripts include correspondence between W.B. Yeats and Shri Purohit Swami, and papers of Jack B. Yeats, Lennox Robinson, Sean O'Faolain, Frank J. Hugh O'Donnell, Ulick O'Connor, Brian Coffey, and the archives of the Proscenium Press and the Raven Arts Press. Comprehensive holdings in American literature include Theodore Dreiser, William Faulkner, John O'Hara, Ernest Hemingway, Herman Melville, Howard Pyle, Carl Sandburg, Harriet Beecher Stowe, Henry David Thoreau, and many others. W.D. Snodgrass, Gilbert Sorrentino, Louis Untermeyer, Jane Heap, Kurt Vonnegut, Tennessee Williams, and the archives of Pagany, A Native Quarterly . A number of works concern travel and exploration, and the history of Delaware from its settlement by the Swedes in 1638 to the present is the focus of the Delaware Collection. Historical manuscripts and archives include the papers, letters, diaries, photographs, account books, ledgers, and records of individuals, families, and organizations.
Regional strengths are Newark and New Castle County , Delaware, and the greater Philadelphia area.
Several collections document Delaware politics and political history . These holdings include the personal papers of Representative Thomas R. Carper, and senators George Gray, Willard Saulsbury, Willard Saulsbury, Jr., J. Allen Frear, and John J. Williams. Collections of broader historical import include the George Handy Bates Samoan Papers, and the papers of career diplomat George S. Messersmith. In addition, the history of American horticulture is richly recorded in books, periodicals, seed catalogs, trade catalogs, prints, broadsides, and the papers of horticulturist and landscape architect Armistead W. Browning.