The collection consists of 4 hardbound volumes of handwritten lecture notes by Michael Henry Bittenger from his time as a student at Princeton Theological Seminary. Notes are for the following courses: didactic theology, taught by Charles Hodge; physics and natural philosophy, taught by John Loomis; church history, taught by James Waddell Alexander; analecta theologica.

The collection consists of papers and other materials covering Gillespie's life as a student, pastor, professor, and administrator. Much of the material includes correspondence and other communications between Gillespie and others. The bulk of the collection spans his presidency at Princeton Theological Seminary.