The Jane M. Rosenthal papers contain a wide variety of historical and contemporary audio recordings, texts, elicitations and grammatical descriptions of Nahuatl, particularly the variety spoken in Tlaxcala, Mexico, both from the research of Rosenthal and others. Fieldwork in Tlaxcala (including photographs), archival research in Mexico and Chicago, and the work of many scholars that formed the Friends of Uto-Aztecan are represented.

An archaeological anthropologist and linguist, John Alden Mason spent the majority of his career at the University Museum of the University of Pennsylvania. After receiving his undergraduate degree at Penn in 1907, Mason received a doctorate at Berkeley (1911) for his ethnographic work on the Salinan Indians of California, but his diverse interests in later years ran the gamut from Puerto Rican folklore to Piman languages and cultures (including Pima, Papago, Pima Bajo, Northern and Southern Tepehuan, and Tepecano), Mayan, Aztec, and Incan archaeology, and the languages of South American Indians. Mason was curator of the University Museum at Penn from 1926 until his retirement in 1958. The Mason Papers include both in-coming and outgoing correspondence, linguistic material, notes, and photographs relating to Mason's work in the southwestern U.S., northern Mexico, and South America. Centered on the years after Mason's return to Philadelphia in 1926, the collection covers all aspects of Mason's professional life, from reports on field work to answering casual questions referred to him through the University Museum to data and analyses on Piman and other languages. The collection also contains voluminous files relating to the Mason's editorship of the American Anthropologist (bulk: 1945-1948). Of special note are a series of class notes (1908-1910) kept by Mason for course work in ethnology, archaeology, and linguistics at the University of Pennsylvania under Edward Sapir and Frank Speck.

The Mary Rosamond Haas papers are extensive, including correspondence, research notes, field notes, texts, lexical slip files, audio recordings, photographs, reprints and more, covering more than 100 languages of North America and Southeast Asia. Of particular value are notes and audio recordings from fieldwork from the 1930s on Ditidaht, Tunica, Natchez and Muscogee, work toward pedagogical materials for Thai, and groundbreaking comparative studies of several language families of North America.