Frank Siebert (1913-1998) is one of the key contributors to the field of Algonquian linguistics. While he did not pursue a degree in linguistics or anthropology, he independently acquired the skills and knowledge of a professional scholar. His work on Penobscot is some of the best and most comprehensive in existence. The Siebert Papers document the interest and work of Frank Siebert in the linguistics of the Algonquian family of languages, particularly Penobscot. The collection includes correspondence, research notes, drafts and published manuscripts by Siebert, as well as secondary sources consulted by Siebert. To a lesser extent, it contains material that documents Siebert's personal life, his interest in book collecting and his career as a physician.

Trained as an anthropologist at Berkeley under A.L. Kroeber and Robert Lowie, Carl Voegelin spent the majority of his career as a structural linguist specializing in Algonquian languages, including Delaware, Potawatomi, Fox, Menominee, and Shawnee, and on the Seneca, Ojibwa (Chippewa), and Blackfoot (Siksika). His most significant contributions came through his studies of Delaware, Shawnee, and Hopi, but he is also credited with reviving the International Journal of American Linguistics after the death of its founder, Franz Boas, and with nurturing the program in anthropology at Indiana University, where he was on faculty from 1941 until his retirement in 1976. The Voegelin collection contains field notes, lexical files, notebooks, papers, correspondence, and other materials relating to Voegelin's work on Native American languages. The bulk of the collection concerns Delaware and Shawnee, but there is significant material for Blackfoot, Menominee, Ojibwa and Potawatomi, Seneca, and Penobscot. Notes on Turkish, kept during the Second World War, are also present. Among other important series in the collection are Voegelin's correspondence and notes concerning two of his major projects: the translation and interpretation of the Walam Olam and his study of Shawnee law. Correspondents include Leonard Bloomfield, Eli Lilly, and Morris Swadesh. A portion of the collection is indexed in Kendall (1982).