Scope and arrangement
The bulk of the collection is made up of De Casseres' manuscripts of his articles, essays, plays, poetry, prose, and editorials. There are numerous clippings of his own writings, articles about him, and those he used as research for his columns and editorials. Among the correspondence there are letters from prominent writers, but one half are his love letters to Bio Terrill. There are a few materials concerning De Casseres' brother.
In 1994, the New York Public Library added eight letters from the poet Edgar Lee Masters to Benjamin De Casseres to these papers. They are filed with the correspondence in Box 1.