Correspondence, manuscripts, notes, notebooks, documents, photographs, course-related materials, and printed materials. The manuscripts include typescripts of Sykes' published and unpublished novels, monographs, plays, short stories, and articles. Among these are The Perennial Avant Garde, The Cool Millennium, and The Hidden Remnant. Sykes' notes and notebooks span the period from the early 1930s to 1980, and include preliminary ideas and sketches for his books, as well as autobiographical material. A small number of documents concern Sykes' wartime work in the U.S. Government Office of War Information. Course-related material including writings and correspondence of students taught by Sykes between 1962 and 1975 at the New School and as an adjunct professor at Columbia University. Printed materials consist of numerous reviews of Sykes' books, in addition to offprints and articles by Sykes. Included as well are printed materials about or connected with Sykes, offprints of articles inscribed to him, and many volumes from his library. The substantial correspondence series includes personal letters and correspondence with agents and publishers relating to his books. Correspondents include Harold Clurman, Aaron Copland, Lawrence Durrell, Georgia O'Keeffe, and Francis Steegmuller, as well as a number of Sykes' students. There is extensive correspondence between Sykes and the artist John Hartell from 1927 to 1983.

The correspondence, research, and teaching files of French-American cultural historian and Columbia University professor emeritus Jacques Barzun (1907-2012).

The Records of the Otto Rank Association, founded by Virginia P. Robinson in 1965 and disolved in 1983.

The editorial and production files of Pantheon Books from 1944 through 1968. The correspondence from authors, agents, and publishers is written to Kurt and Helen Wolff, Jacques Schiffrin, André Schiffrin, and the editors of the firm. The files document the publication of works by A. Alvarez, Georges Bernanos, Hermann Broch, Jacob Burckhardt, Albert Camus, William Demby, Eugene Ionesco, Karl Jaspers, Winifred Bryher, Jacques Maritain, Isamu Noguchi, José Ortega y Gasset, Pier Paolo Pasolini, Sir Herbert Read, Ben Shahn, and others.