The collection consists primarily of correspondence among Cowper, his family, friends, and editors. The primary correspondents include Sir John Carr, William Hayley, Lady Hesketh, John Johnson, Mrs. King, John Newton, Samuel Rose, and Samuel Teedon. Additionally, there are assorted poetry and prose manuscripts by both Cowper and others, including "The Norfolk Mss" and "The Four Ages" by Cowper; epilogue to The Sea-Side Hero and dedication to Lord Moira for The Stranger in Ireland by John Carr; and passage for "Life of Crashaw" and passage for Lord Sheffield's edition of Gibbon's Miscellaneous Works and Memoirs by William Hayley. Among the memorabilia and miscellaneous materials are engravings of Cowper, receipts signed by Alexander Pope, a fragment of Cowper's "Yardley Oak," and tombstone rubbings of Cowper's family.

Titles of bound volumes in the collection:

bd. vol. no. 1 = Cowper / Hesketh correspondence

bd. vol. no. 2, v. 1-2 = Cowper / Newton correspondence, I. 1771-1784 and II. 1785-1797

bd. vol. no. 3 = Cowper / Teedon correspondence in bound volume

bd. vol. no. 4 = Newton / Thorton correspondence

bd. vol. no. 5 = "A Vindication of Hayley's Life of Cowper"

bd. vol. no. 6 = Commonplace book

bd. vol. no. 7 = "Abridgement of Rev. Dr. Thomas Burnet's A Treatise Concerning the State of Departed Souls, Before, and at, and After the Resurection "

bd. vol. no. 8 = "The Norfolk Mss"

bd. vol. no. 9 = Unpublished poems by Willian Cowper, Esq.

bd. vol. no. 10 = "The Four Ages"

The following standard abbreviations, or their variations, are used to identify materials in this collection: ALS = autograph letter signed, ANS = autograph note signed, AMs = autograph manuscript, n.y. = no year.