Papers pertain mostly to Menzel's professional activities and scientific reasearch and writing, with some personal and Harvard related material. Includes correspondence with societies (International Astronomical Union, International Scientific Radio Union), U.S. Navy and Air Force, publishers, and various individuals, such as prominent scientists and students. Of particular interest is his correspondence with John F. Kennedy (1959-1963) regarding a variety of scientific and political concerns. Other related material includes proposals, contracts and reports concerning cryptanalysis, solar and other research for the U.S. government and corporations; reports, photographs, and engineering drawings for the Harvard College Observatory; and financial and other reports, blueprints, policy manuals and organization charts from various Association of Universities for Research in Astronomy projects. Writing files include manuscripts, notes and scientific data, outlines and related correspondence for scientific and popular works. Also manuscript of autobiography and his creative writings and drawings. Personal material includes photographs, scrapbooks, transcript of U.S. Air Force security hearing board in 1950. Related publications and reference material also available in repository.