Michael Sadleir was an author, publisher, and bibliographer. The collection includes professional correspondence, writings, photographs, and research material documenting Sadleir's career as author, publisher, and bibliographer; and personal and family material, including genealogical material, family correspondence from the eighteenth and nineteenth centuries, photographs, and financial material. Included are letters from authors, publishers, librarians, illustrators, book collectors, and others writing to Sadleir in his capacity as publisher at Constable and Company, as editor of the magazine as author, and as bibliographer. Notable correspondents include D. H. Lawrence, members of the Trollope family, Walter De la Mare, Dorothy Sayers, and Vita Sackville-West. Sadler family correspondence includes letters of Michael Thomas Sadler (1780-1835), a member of Parliament and leader in social reform; letters from Michael Sadleir's sons, Richard and Michael Thomas Carey Sadler (1916- 1942), during their World War II service; and other family letters. Other materials include writings by Sadleir; subject files kept by him on Bentley Publishing House, London, Edward Bulwer Lytton, Anthony Trollope, and other subjects; family pictures; and photographs used to illustrate various books and articles by Sadleir. Rhythm,
