The Arthur Caswell Parker Papers contains correspondence including letters written by Ely Samuel Parker, as well as Frederick Ward Putnam, Horace Porter, Theodore Roosevelt, Nathan L. Miller, Allen Macy Dulles, Woodrow Wilson, James Schoolcraft Sherman, William Howard Taft, and Lewis Henry Morgan. This collection also includes Parker's extensive research, published and unpublished articles, and lectures on museums, archaeology, and American Indians, particularly those of New York State, including their history, culture, problems, legislation, administration, rights and citizenship. Related topics include the American Indian in World War I, American Indian Day, Harriet Maxwell Converse, Cornplanter, Lewis Henry Morgan, Mary Jemison, the Parker family, and Red Jacket. There are six volumes of radio scripts delivered in 1937 through 1938 under the title A Romance of Old Indian Days as well as the 1943-1944 radio scripts of the Rochester War Council's Speakers' Bureau.

The Ely Samuel Parker Papers are comprised of one box containing mostly manuscript material, including approximately 30 letters to or from Ely Parker; legal and business material; two leather notebooks from the 1850s and 1860s; and some items that were removed in January 1972 from the extra-illustrated volume The Life of General Ely S. Parker by Arthur C. Parker.

Manuscripts of published and unpublished works of George Henry Harris including manuscripts (presumably an original and a revised draft) of his "Life of Horatio Jones."

The papers include correspondence to and from Morgan, manuscripts of articles and speeches, manuscript notebooks and travel diaries, and the manuscripts of several of his books. Correspondents include Henry Adams, Adolph F. Bandelier, Charles Darwin, Joseph Henry, Francis Parkman, and Herbert Spencer.