Correspondence, manuscripts, documents, photographs, memorabilia, scrapbooks, and printed material. Among his correspondents represented in the collection by at least 75 items are: William Archer, Hobart C. Chatfield-Taylor, Augustin Daly, Austin Dobson, Hamlin Garland, Bronson Howard, William Dean Howells, Henry Arthur Jones, Henry Cabot Lodge and Thomas Raynesford Lounsbury. There are bound volumes of letters from Henry C. Bunner, Andrew Lang, Rudyard Kipling, Theodore Roosevelt, miscellaneous letters to Matthews, and Matthews' editorial correspondence with the North American Review. There are three boxes of manuscripts, including poems by 21 authors; essays on drama; and plays by Henry Arthur Jones, Don Marquis, and Matthews; bound volumes of manuscripts of Matthews' plays and his book, "Development for the Drama." Also included are 17 boxes of his manuscript notes for his many lectures, articles, and books; and memorabilia, primarily from the theatre and from his life at Columbia. Material on the Dunlap Society, which was devoted to printing works relating to the theater, of which Matthews was co-founder with Laurence Hutton, includes documents and correspondence, much of which is between then secretary Evert J. Wendell and members on meetings and other Society business around 1914. In addition, there are notes and correspondence of Herbert Kleinfield relating to his research on Matthews.