Consists of correspondence from 1923-1986, including general letters, family correpondence, and letters relating to the publication of Burt's writings. Most of the letters are written to Nathaniel Burt, although some drafts and originals of letters written by him are also present.

The prolific family correspondence includes letters from Struthers Burt (father) and Katharine Newlin Burt (mother)—both noted writers—Julia Burt Atteberry (sister), Margaret Clinton Burt (wife), and many others. The publishing correspondence consists of letters from many publishers, but the bulk is from Little, Brown & Company of Boston, Nathaniel Burt's primary publishing house. Royalty statements and extensive correspondence from the firm of McIntosh & Otis—Burt's literary agency—are also contained in the publishing sub-series. Also included are invitations to various weddings, parties, and ceremonies, and also any unidentified correspondence.