This group of material consists of letters to Hartley from others. Correspondents include artists, writers, cultural figures, and institutions, including Hart Crane, Robert McAlmon, Henry Miller, Marianne Moore, Arnold Ronnebeck, Elizabeth Sparhawk-Jones, Gertrude Stein, Alfred Stieglitz, Carl Van Vechten, William Carlos Williams, Edmund Wilson, and others. There are also a number of correspondents with ties to Hartley's home state of Maine.