This collection reflects a wide variety of the activities of the Reverend John Cleaveland. The collection is divided into three series.

Series I. Personal Papers includes biographical papers as well as correspondence John wrote to his wives, family, and friends. Of particular interest in John's biographical papers is a journal kept of his years at Yale College; his confession given to the "Reverend Rector and tutors of Yale;" and the document expelling John and Ebenezer from that school. Also included are a fragment of John's autobiography; a document confirming John as chaplain to Colonel Bagley; and John's will and personal account records.

John's correspondence with his wives includes his marriage proposal to Mary Dodge, letters exchanged while John was Chaplain to Colonel Bagley during the French and Indian War, and letters to Mary (Neale) Foster from Prospect Hill during the American Revolution. His family correspondence includes letters between John's parents and their children, between John and his brothers, and between John and his children. John's correspondence with his friends is primarily religious exhortations.

Series II. Church Papers consist of sermons and testimonials, correspondence, and church administration. The sermons and testimonials are primarily stories of individual conversion to Christianity, as well as replies to criticism of the separatist group in particular. The correspondence consists of letters between various separatist churches and letters defending the separatist view to those in other denominations. Of special interest is a rebuke given to John Cleaveland for ministering in a church without the pastor's consent, and the invitation to and response of John Cleaveland to pastor the "New Gathered Church of Christ at Chebacco in Ipswich". Church administration papers include formal religious doctrinal writings of the separatist churches, covenants uniting the Second and Fourth Churches of Ipswich into one Congregational Church, and records of church committee meetings.

Series III. Family Papers include correspondence written by John's family, genealogical information on the Cleaveland family, legal papers from John's wife, parents and siblings, Mary (Dodge) Cleaveland's diary, and the remainders from a scrap book. Also included are diplomas, appointments, and membership certificates for multiple generations of the Cleaveland family as well as a poster guide of short hand from 1823.

The collection was originally bound as a 4-volume scrapbook, but has since been dismantled. Many documents are adhered with wax to groups of other letters based on an original order established in the scrapbook.