Proofs, photographs, photostatic copies, and other printed materials of Roscoe. Included are proofs and illustrative materials for his book The Web Of Conspiracy; The Complete Story Of The Men Who Murdered Abraham Lincoln, and a printed copy of his book, Only In New England, a book of crime fiction.

Correspondence, manuscripts, notes, memoranda, notebooks, notecards, proofs, photographs, microfilms, and printed materials. The Papers include the manuscript research materials and correspondence for each of his books except his biography of Theodore Dreiser. Among the correspondents are William Benton, Bruce Catton, Carey McWilliams, Mrs. Fremont Older (Cora Miranda Baggerly Older), and Thornton Wilder.