Copies of 82 vocabularies representing 73 languages with notes and additions made by Du Ponceau and Albert Gallatin. Vocabularies for South American languages are copied from rare printed sources, while North American vocabularies are from both printed and manuscript sources. The first 23 pages of the volume are the Continuance Docket of the Court of Common Pleas, Philadelphia County, 1783-1786. Cases noted are those involving Stephen Dutilh, Samuel Garrigues, John Girard, John Holker, Charles J. de Longchamps, and Claude P. Raguet.

A pioneer in ethnographic and linguistic studies of the American Indian and one of the most active members of the American Philosophical Society, Peter Stephen Du Ponceau helped to establish the American Philosophical Society's reputation as one of the world's foremost centers for the study of American Indians and their languages. The Peter Stephen Du Ponceau collection consists of correspondence on legal matters, Indian linguistics, silk culture, maritime law, the American Philosophical Society, and various publications of the early nineteenth century. The collection also includes several essays by Du Ponceau, most of which deal with maritime law.