The collection contains photostats of over 100 Washington letters in the private collection of Edward Ambler Armstrong, original Washington letters and documents, and several supplementary items. Included is an original survey (1750) of land in Frederick County, Virginia, made by Washington for Isaac Pennington. While many of the letters deal with military affairs of the Revolutionary War, Washington's management of his estate, Mount Vernon, including a list of persons he and Martha enslaved (1799), and that of the government during his presidency are also prevalent topics in others. Correspondents include George Clinton, Alexander Hamilton, James Madison, Robert Morris, and Bushrod Washington.

Also included in the collection are two letters by Washington addressed to Major William DeHart of the New Jersey Regiment: the first, sent from Trenton, N.J., on January 1, 1777, regards the appointment of Col. Newcomb; the second, written at Morristown, N.J., and dated January 8, 1780, concerns provisions for the Continental Army. One letter to Col. Dayton of Chatham, N.J., dated June 14, 1781, concerns the movement of the British fleet; another to Edward Pemberton in London mentions the Revolutionary War. Included are a letter by Washington to the Rev. Jonathan Boucher, schoolmaster of Washington's stepson, Jack Custis, about paying for the boy's tuition, clothing, and the stabling of his horse, and a letterpress copy of a letter sent by Washington to his mother, Mrs. Mary Washington. In adddition, there is a copy of a letter by Jacob Duché to George Washington, dated December 8, 1777, asking him to stop rebelling against England, as well as a note from Richard Price which accompanied a presentation copy of a pamphlet Price wrote about Washington.

Documents signed by Washington include a certificate of membership of John Lawrence in the "Society of the Cincinnatis" and another appointing William Patterson of New Jersey to the Supreme Court. In addition, there is his survey, dated November 24, 1750, for a tract of land (453 acres) that he purchased in West Virginia.

Material by members of Washington's family includes a letter from John Augustine Washington to "Mrs. Morgan," dated December 25, 1860; three letters (1808, 1818, and 1826) and three engravings of Bushrod Washington; and a letter from Henry Augustine Washington, Princeton Class of 1839, to his father, Lawrence Washington, dated June 18, 1847. There is also a letter from Lawrence Washington certifying the authenticity of the signature and bookplate of George Washington which he sold, giving the successive ownership of the book in which they appear. This letter is dated October 17, 1904.