The collection of about 850 items covers the period from 1782 to c. 1936, with the bulk dating to the 1780s to 1840s. The collection is divided into four series. Series I contains correspondence relating to a wide variety of topics, including French and English politics, business, trade, religious matters, and personal affairs. Many of the items are letters of introduction. There is also information on John Vaughan's immigration to America, Joseph Priestley, vaccines and inoculation (with Jefferson's comments on the same), Vaughan's business in Philadelphia, and the American Philosophical Society. Also included in this series are 2 boxes with copies of Vaughan correspondence as well as miscellaneous notes by E. W. Madeira, gathered in the course of his research on Vaughan in the 1930s. Series II consists of three volumes. Included are two of Vaughan's commonplace books. One, entitled, "J. Vaughan's book," May 17, 1779 (47 pp., in Latin; 870/L34), includes mostly Latin notations. The other commonplace book, dated 1783 (ca. 66 pp.; B V 462.c), includes comments on several prominent Americans, such as Benjamin Rush and David Rittenhouse, as well as American society generally. The third volume is a copybook with thirty letters spanning the period 1784 to 1801 (B V462.1). Series III includes material relating to Vaughan's administration of the estate of the Philadelphia merchant Samuel Merrick, 1796-1822 (Vaughan-Merrick Papers, B V462.m; 2 boxes). Series IV consists of correspondence between Vaughan and the DuPont Co. for which he served as agent (B V462.4; photocopies of 73 letters).

This volume contains short sketches of prominent American and European scholars, diplomats, and statesmen. "These short memoirs were composed in the heat of the summer of 1862; and the concluding page written on the 15th of August of that year, when I was about one month advanced in my ninety second year; my birthday being July 17th, 1771." Signed Saml. Breck. Persons discussed include Talleyrand Perigord; M. Volney; Rochefoucauld Liancourt; Louis Philippe, King of the French; Joel Barlow; William Bingham; Robert Morris; Alexander Hamilton; General Henry Knox; Doctor Benjamin Rush; Doctor Rush and William Cobbett.

This collection consists of facsimiles of documents, microfilmed for "Philip Mazzei: the comprehensive microform edition of his papers, 1730-1816" (Kraus International Publications, 1982), and also typescripts and translations into English of other documents.