These papers reflect Maria Mitchell's professional life and include thirty-one notebooks of astronomical observations; observatory photographs; manuscripts, notes, and drawings; letters regarding the Nautical Almanac computations, 1853; notes for preparing Vassar College Astronomy Dept. reports, 1871-1886; and correspondence, 1861-1889, including her letters to Benson J. Lossing, Ann Eliza Morse, John H. Raymond, Mrs. John H. Raymond, Cyrus Swan, and James Monroe Taylor, and letters from James Edward Oliver, Arthur Searle, Rufus Babcock, Charles Farrar, Nathan Bishop, and Vassar College Presidents John H. Raymond and James M. Taylor. Other items include research correspondence about Mitchell, 1907-1974; excerpts from Vassar College Trustee minutes and copies of correspondence regarding the Astronomy Dept., the Observatory, and Mitchell's salary, 1862-1872; publications by Mary W. Whitney, Mary King Babbitt, and others about Mitchell; and letters from Helen Wright concerning her biography of Mitchell, circa 1949.