The Scientists Collection is comprised of individual letters and small groups of correspondence from American, British, French, and German scientists during the past three centuries. Although the content is highly varied, there is significant strength in astronomy, natural history, conchology, and geology. Among the scientists better represented in the collection are the astronomers William Radcliffe Birt, J.F.W. Herschel, and Franz Xaver von Zach; the conchologists A.D. Brown, Fred L. Button, Otto Mörch, Alfred Newton, Christian M. Poulsen, Temple Prime, Benjamin Lewis Vulliamy, and A. G. Wetherby; the physical scientists George Biddell Airy, Arnold Sommerfeld, Ferdinand R. Hassler, and Max Planck; the archaeologist Jean François Nadaillac; the philosopher William Whewell; and the naturalists Walter Henry Bates, Robert Chambers, Edme Dupuget, Robert Kaye Greville, Joseph Henry, John Stevens Henslow, John Lubbock, and Herbert Spencer.

Arthur J. Cain is an evolutionary biologist whose research interests have included genetics, natural selection, biogeography, and systematics. Based at Oxford University and, later, the University of Liverpool, much of Cain's research was field-based, focusing on terrestrial gatsropods. This collection contains correspondence, grant applications, reports, programs for scientific meetings, unpublished papers and lectures, research notes, charts, graphs, maps, and manuscript reviews of journal articles and books. The Cain Papers is divided into three series: I. Correspondence ; II. Subject Files ; and, III. Papers by Colleagues. Arrangement is alphabetical by folder title, and chronological within each folder.

One of the seminal figures in the emergence of the Modern or Neo-Darwinian Synthesis during the mid-twentieth century, George Gaylord Simpson (1902-1984) helped define the unique contribution made by vertebrate paleontology to the life sciences. A specialist in Mesozoic and early Cenozoic mammals, Simpson's contributions to the fusion of Darwinian natural selection and Mendelian genetics were both empirical and theoretical, culminating in his major works Tempo and Mode in Evolution and The Meaning of Evolution. From his posts at the American Museum of Natural History (1927-1959), Columbia University (1945-1959), Harvard (1959-1967), and the University of Arizona (1967-1984), Simpson became one of the most influential paleontologists of the century, helped in part by his ability to write successfully for both a technical, professional audience and a popular audience. The Simpson Papers include a comprehensive assemblage of professional and personal correspondence, reflecting nealy all phases of Simpson's career. Written with charm, wit, and a sense of literary style, the correspondence touches on all aspects of modern paleontology, providing an important perspective on the emergence of contemporary evolutionary theory, biogeography, systematic theory and methodology, the relationship of science and religion, and creationism, as well as more general issues in scientific epistemology and social and political issues. The collection also includes autobiographical data and writings, lectures, class notes and papers, research data, material on his scientific expeditions (diaries in carbon form, photos, notes, etc.), publication material (he was author of some 800 publications), extensive photographic material, diplomas, and medals.

Sewall Wright ranks among the most influential figures in the field of population genetics during the 20th century, and made important contributions to biostatistics, biometrics, and evolutionary theory. These papers contain much of Wright's professional correspondence, scattered research notes, and drafts of a small number of papers.