The collection contains approximately 300 letters written to Sala by about 200 different people over the course of 40 years. Included in the collection are letters, usually single, by prominent authors, journalists, artists, nobility, philanthropists, and other notables, such as Sir Edwin Arnold, P. T. Barnum, Dion Boucicault, M. E. Braddon, Wilkie Collins, Lady Mary Combermere, George Cruikshank, Charles Dickens, Jean Henri Dunant, Emily Faithful, Lord Ronald Gower, W. Holman Hunt, Sir Henry Irving, Charles G. Leland, Horace Mayhew, Arthur Orton (the Tichborne claimant), Charles Reade, Henry Vizetelly, Thomas Woolner, and Edmund Yates.

Additional accessions include letters written by Sala to various correspondents, including Richard Edgecumbe, William Powell Frith, Sir Charles Hall, Joseph Jefferson, Parke Godwin, Lady Monckton, and John Busrand Payne. Also included is a letter from Ralph Straus, who seems to have been the original owner of the 300 letters, to de. V. Payne Payne regarding Sala, dated Sept. 6, 1939.