Dr. O’Toole areas of interest lay in Boston history, Catholic history, American religion and the history of American Catholicism, the history of religious practice and popular devotional life. Dr. O’Toole is the author of, The Faithful: A History of Catholics in America; Passing for White: Race, Religion, and the Healy Family; Militant and Triumphant: William Henry O'Connell and the Catholic Church in Boston, 1859-1944. He is the co-editor of Boston's Histories: Essays in Honor of Thomas H. O'Connor. Dr. O’Toole is studying the history of the practice of confession in America and is currently writing a new history of Boston College. His expertise has been utilized by several media entities including the New York Times and Atlantic Monthly.