Correspondence, manuscripts, notes, technical reports, memoranda, questionnaires, interview schedules, personal and professional documents, several photographs, one tape recording, and printed materials. The correspondence files contain letters to colleagues and researchers such as Bernard Berelson, Robert Lynd, Robert Merton, and Frank Stanton. The subject files document Lazarsfeld's many research projects such as the Admissions Officers Project, 1964-1970, the Planning Project for Advanced Training in Social Research, 1950-1955, and his first major endeavor, the Princeton Radio Research Project, 1937-1940. There are complete records for his 1954-1955 study on McCarthyism's effect on college teaching. These original materials consisting of correspondence, interview schedules, and questionnaires contain many detailed comments which could not be included in the published version of this study, THE ACADEMIC MIND (1958). Numerous files relate to Lazarsfeld's position as Associate Director of the Bureau of Applied Social Research (BASR). There are manuscripts of books, research papers, lectures, and articles by Lazarsfeld as well as by his students and colleagues.

Correspondence, writings, reports, memoranda, case files, and related printed materials. The papers cover the entire field of law with particular emphasis on civil rights, labor law, and family law. They include several series of office files dealing with Columbia University Law faculty, students, his course materials, and the administration of the Law School. In addition, there are numerous files for Amherst College (from which Gellhorn received his A.B. degree), arbitration cases, federal administrative procedure, legislation, the American Civil Liberties Union, the Association of American Law Schools, and Fordham University (for which he prepared a study). There are manuscripts, drafts, proofs, correspondence, and other related materials for some of his books: Administrative Law Cases and Comments (1940); Security, Loyalty and Science (1950); The States and Subversion (1952); Individual Freedom and Government Restraint (1956); When Americans Complain (1966); and Ombudsmen and others (1966).