Professional and personal correspondence; notes, galleys, and manuscripts of books written by O'Connell; articles and reviews collected or written by O'Connell; and collected sermons given by O'Connell, with a tape recording of his sermon for the consecration of Bishop James P. Shannon (31 March 1965); also a full run of clippings and typed submissions of a newspaper column, written by O'Connell, 1966-1974, on a wide variety of religious, social and political topics; and photographs.

Galleys from his book on John Ireland (1988) and related correspondence and reviews; speeches with related letters; and other personal and professional correspondence; Xerox copies of reviews of his book on John Ireland; letter recommending O'Connell for fellowship to Notre Dame, 13 April 1956; correspondence 1991-1998, re Notre Dame and O'Connell's activities, including London Program correspondence 1993-1995; speeches, some published some not; material related to his column "Tracts for the Times" 1966-1974; and reactions to his books on Pascal and Modernism.