The collection includes material built from Callahan’s works as a renowned scholar, writer and educator, including Callahan’s notes, drafts and related correspondence surrounding his work as Ralph Ellison’s Literary Executor and as an Ellison scholar. The uniqueness of the collection provides researchers access to never-before-seen notes and sketches on the work of Ralph Ellison, the acclaimed African-American author of "Invisible Man", as well as insight into Ellison scholarship from one of the foremost experts in the field.

Callahan, a close friend to the Ellison family, was named Literary Executor to the Ralph Ellison Estate by Ellison’s widow, Fanny McConnell Ellison, following Ralph’s death in 1994. The collection includes: an extensive amount of material by Ralph Ellison in facsimile, including copies of the collected correspondence of Ellison, the originals of which rest at the Library of Congress; numerous rare original publications containing Ellison work; copies of many of Ellison’s earliest stories and drafts; and translations of Ellison texts in over 20 languages.

Callahan has written or edited numerous volumes related to African-American and 20th century literature Including "The Illusions of a Nation: Myth and History in the Novels of F. Scott Fitzgerald", 1972; and "In the African-American Grain: The Pursuit of Voice in 20th Century Black Fiction", 1988. African American literature and the work of Ralph Ellison have been a focus of Callahan’s scholarly work since he published the 1977 article “The Historical Frequencies of Ralph Waldo Ellison” in Negro American Literature Forum (now African American Review). As an Ellison scholar Callahan has also published Ellison’s "Invisible Man", 2001; Ralph Ellison’s "Invisible Man : a Casebook", 2004; Callahan edited the Ralph Ellison short story collection "Flying Home and Other Stories", 1996 and "The Collected Essays of Ralph Ellison", 1995; Co-edited with Albert Murray the Modern Library edition of "Trading Twelves: The Selected Letters of Ralph Ellison", 2000. As the Literary Executor to Ralph Ellison, Callahan worked as the primary editor for the posthumously-released Ralph Ellison novel "Juneteenth", and the complete edited manuscript "Three Days Before the Shooting…", 2010. Callahan’s own literary work includes the novel "A Man You Could Love", Fulcrum Publishing, 2007, and the upcoming novel "The Learning Room." Callahan is currently in the process of completing the trilogy with the novel "Belonging".