The Rossetti collection consists of three series: Dante Gabriel Rossetti letters, William Michael Rossetti letters, and miscellaneous materials. The entire collection contains approximately 80 items dating from 1865 to 1900, including letters written by Dante Gabriel Rossetti between 1865 and 1868. The bulk of the collection consists of letters written by William Rossetti between 1897 and 1899 to Francis W. Burgess, a London bookseller, and Burgess’s widow, dating from 1899 to 1900. This correspondence concerns the sale of Gabriel and Christina Rossetti's works and touches on other topics, such as pirated editions of Gabriel's books and complaints about the maintenance of his grave. William Rossetti often mentions poets William Blake and Percy Bysshe Shelley, of whom he was one of the earliest appreciative critics.

The group of miscellaneous materials include a list of books William Rossetti considered selling to Francis Burgess; a clipping from a printed bookseller’s catalog with a transcription of correspondence from William Blake to Hayley dated October 7, 1803; a clipping from the Daily News from April 26, 1898 with a letter to the editor written by Francis Burgess; correspondence from William Rossetti about the condition of the grave of Dante Gabriel Rossetti; an envelope addressed to Ford Madox Brown that includes the monogram of the Pre-Raphaelite Brotherhood; a clipping from The Atheneum dated December 4, 1898 with a letter to the editor written by William Rossetti; two copies of the program from the burial service of Christina Rossetti dated January 2, 1895; nine envelopes and postcards addressed to F. W. Burgess; and six checks from Francis Burgess to William Rossetti dated from 1897 to 1898.