The plant physiologist and historian Rodney H. True (1866-1940) divided his career relatively evenly between the Bureau of Plant Industry in United States Department of Agriculture and the Department of Botany and Morris Arboretum of the University of Pennsylvania. A specialist in the physiological function of mineral nutrients in plants, True was active in his later career in the Philadelphia Society for Promoting Agriculture, the Pennsylvania Horticulture Society, and the Agricultural History Society. The True Papers consist of 6 linear feet of material relating primarily to the period of his career spent at the University of Pennsylvania. The collection contains roughly equal proportions of personal and professional correspondence, with a few diaries and research notebooks documenting his involvement with professional organizations and his interests in the history of his discipline.

The collection contains information on Fox family speculation in western lands, two manuscript maps from the 1790's and 1830's depicting the family's holdings in northwestern Pennsylvania, and a photograph album from the 1890's documenting Chestnutwold, the Fox estate adjacent to Andalusia. Chief correspondents are Samuel and George Fox.

After a brief career in the Congregational church, J. Peter Lesley (1819-1903) left the ministry in 1852 to work full-time as a geologist. Having gained experience in structural geology and stratigraphy with the First Pennsylvania Geological Survey (1836-1842), Lesley became an expert in the geology of coal, working for the Pennsylvania Railroad and other corporations and conducting some of the first systematic studies of the state's hydrocarbon resources. A long-time professor at the University of Pennsylvania, he was elected to the APS in 1856, serving variously as its librarian, secretary, and vice president, and he was selected as Director of the Second Pennsylvania Geological Survey (1875-1889). The Lesley Papers include letters to and from Peter Lesley and his wife, Susan on geology, coal and iron mining, abolition, educational reform, organized charity, and Unitarianism. The collection offers important insight into academic and applied geology in late 19th century Pennsylvania, the development of the coal and iron industries, as well as into the Lesleys' progressive social and intellectual milieu. It is divided into three series: Lesley's general correspondence, his correspondence with his brother Joseph, and microfilms of Lesley's research notes.

Frederick Henry Osborn was an administrator, humanist, and scientist. This collection includes letters, diaries, reports, speeches, drafts of articles and books, oral history interviews, and photographs. There are diaries and letters for his service in Europe with the American Red Cross during World War I. There are some letters and documents, such as patent applications and plans for inventions, from his "business career" period prior to 1928, after which he became a research associate at the American Museum of Natural History studying anthropology and population. This study led to his later important contributions to the redirection of eugenics study in the U.S. and the reorganization of the American Eugenics Society. His other related organizational work and publications relating to human and population genetics are also documented in this collection. There is significant material (letters, diaries, reports) related to Osborn's World War II contributions as the chairman of the Civilian Committee on Selective Service in 1940, and as head of the Morale Branch of the U.S. Army (later, the Information and Education Division of Special Services) in 1941. Also included are important documents, especially his diary, from his work as deputy representative on the U.S. Atomic Energy Commission and the U.N. Commission for Conventional Armaments. His letters, writings, and speeches relating to foreign policy are extensive, spanning the period from the 1940s until his death, much of it from the Vietnam War years. The correspondence with Kathleen Harris is particularly rich in this respect. There is family correspondence reflecting his dynamic philosophy of life, with long series of letters to his parents (1917-1945) and to his children and grandchildren. His later civic and regional interests, as a long-time resident of Garrison, N.Y., are evidenced in the work he did on the Palisades Interstate Park Commission.

The Franz Boas Personal and Professional Papers contain a diverse assemblage of professional correspondence, family letters, and diaries, with a valuable series of essays and lectures by Boas on both professional and political topics (democracy, race, etc.). (NOTE: This collection is not to be confused with the much larger Franz Boas Papers collection (Mss.B.B61), which contains the vast majority of Boas's professional correspondence and was referred to as the "Professional Papers" in earlier decades.) During the half century leading up to the Second World War, Franz Boas helped to define academic anthropology in the United States. Trained as a geographer at the University of Heidelberg, Boas worked initially on the Inuit of Baffin Island and subsequently on the cultures of the Indians of the Northwest Pacific Coast, becoming a leading figure in American anthropology by the first decade of the twentieth century. As Professor of Anthropology at Columbia University, Boas made significant theoretical contributions to ethnology, linguistics, and physical anthropology, helping to ingrain the four fields approach in his discipline and introducing the concept of cultural relativism into wide currency. He was, as well, a committed Socialist and an ardent opponent of both racism and fascism.