This item contains Jefferson's comparative vocabulary, based on his collection of vocabularies taken on printed forms; a second comparative vocabulary; and John Sibley's vocabulary of the Caddo language. This document was damaged in transit from the White House to Monticello in 1809 (see letters of Jefferson to Peter S. Du Ponceau, November 7, 1817, and April 26, 1816.)

Beginning in the 1790s, the American Philosophical Society began to accumulate vocabularies and texts written in Native American languages, guided by Thomas Jefferson's idea of using comparative linguistics to reconstruct the histories of Indian peoples and discern their origins. The American Indian Vocabularies Collection was initially assembled by the Historical and Literary Committee of the APS for publication in 1816. They include information on seventeen North American languages and one each from the Caribbean and Central America, collected between 1784 and 1828. A number of individuals were invovled in recording the vocabularies, including Benjamin Hawkins, William Thornton, David Campbell, Daniel Smith, Constantine Volney, Constantine Rafinesque, William Vans Murray, John Heckewelder, Martin Duralde, Campanius Holm, and Jefferson himself. Most followed the standardized word set established by Jefferson.