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.