The Correspondence series includes letters to and from Milton Friedman, Lytle's general correspondence, and his correspondence with publishers. Materials are arranged in chronological order. The single folder of correspondence with Milton Friedman ranges from 1988 to 1992 and includes discussions of Lytle's writing and voucher systems and school privatization in general. Two folders of general correspondence dating from 1974 to 1993 document a range of issues related to education through inquiries and contacts made by Lytle in the course of his research. The single folder of publisher correspondence tracks Lytle's dialogues with a variety of publishers, primarily in reference to his submissions.