Correspondence, writings, research files, personal papers, photographs, printed material and other papers documenting both the professional and personal activities of Donald Gallup as scholarly bibliographer, editor, curator of the Yale Collection of American Literature, and book and manuscript collector on his own account. The majority of the collection consists of Gallup's own papers, including personal, professional and editorial correspondence; a small amount of personal papers; research files; and typescripts and galley proofs of many of his publications, including his editions of the journals of Thornton Wilder and several volumes of works by Eugene O'Neill. Correspondents include the authors James Purdy, Sheri Martinelli, and Mary Bernetta Quinn and the Yale librarian James T. Babb. In addition, the collection contains some of the letters and papers by Modernist writers collected by Gallup personally and donated by him to Yale. The most extensive of these groups is the collection of letters by T. S. Eliot in Group X. Recipients include Arnold Bennett, Richard Cobden-Sanderson, Edgar Jepson, Alida Monro and Harold Monro, Brigit Patmore, John Carroll Perkins, and Donald Gallup himself. Publishers' correspondence and book contracts of Carl Van Vechten are found in Group V., while Group VII. and Group VIII. contain copies of articles and ephemera by and related to Ezra Pound and a small amount of Pound correspondence. Diaries by Carlotta Monterey O'Neill are located in Group X.