Papers of the family of Augustine Prevost III (1744-1821), a British soldier in the French and Indian War and the Revolution, who remained in New York after the war and settled on land in Greene County. He was married twice, to Susannah Croghan and to Ann Bogardus; the first family was brought up in Britain and the second in America. Papers include letters between the British and American sides of the family, between the American Prevosts and their neighbors, the Thomas Cole family, and with Sir William Johnson, George Croghan, Sir Frederick Haldimand, Colonel Henry Bouquet, General Morgan Lewis, and the Duke of Kent. Other items include memorandum book of the 3rd Battalion, 60th Foot, Royal American Regiment, from St. Augustine, Florida, 1777-78, which contains an inventory of the estate of George Croghan, 1783; map of Prevost lands in Greene County; and miscellaneous receipts, bills, deeds, wills, and genealogical records.

The Pruyn Family Papers contains documents relating to three consecutive generations of the John Pruyn Family, along with genealogies and personal papers of more distant family relations. An autograph collection of presidents, statesmen, and local historic figures is included. The ownership of 43-45 North Pearl Street is documented from the first sale in 1679 to the last in 1968. The estates of Eleanor Erving, Justine Bayard Erving and Van Rensselaer Pruyn are also documented.