Arranged in two main categories: correspondence and diaries. Three folders of biographical materials precede the correspondence. Four folders of notebooks and one folder of publications and bibliographies follow the diaries. The papers illuminate Crew's multiple roles as an experimental scientist, an educator, and an historian of science. Much of the correspondence revolves around the current state of scientific inquiry with discussions of experiments in solar research and instrumentation, collaborative work in publishing texts and sharing materials, and opinions solicited and given on candidates for academic and administrative posts. Crew's correspondence covers the years 1882 to 1953. With the exception of two folders of Crew family correspondence, the vast bulk of the correspondence is with other physicists, astronomers, and scientists, including: Joseph Sweetman Ames, John Alfred Brashear, George Ellery Hale, Albert Abraham Michelson, Robert Andrews Millikan, Henry A. Rowland, Ernest Rutherford, Arthur Gordon Webster, and Robert William Wood. Crew was a dedicated diarist and his 47 diaries (1876-1953) provide a splendid record of his daily professional and personal life. The diaries are indexed from 1930 to 1952 by individual names, events, and organizations.