The collection consists of works, correspondence, documents, and other material of Conklin. Included are manuscripts and notes of articles, lectures, and speeches, many of which reflect his life-long interest in three organisms, crepidula, cynthia (styla), and amphioxus, as well as Darwinism, and heredity and environment; correspondence regarding scientific, academic, and personal matters; material relating to professional (Marine Biological Laboratory, Woods Hole Oceanographic Institute, the Scripps Institution of Oceanography, and Rockefeller Institute for Medical Research) and academic (Phi Beta Kappa and The American Scholar, and various groups at the University of Pennsylvania and Princeton) interests; and papers regarding organizations in which Conklin was involved, such as the American Association for the Advancement of Sciences, the American Association of University Professors, the American Philosophical Society, the Carnegie Foundation for the Advancement of Teaching, the Carnegie Institution, the National Academy of Sciences, the National Research Council, and the Wistar Institute of Anatomy and Biology. The collection also contains many slides used by Conklin to illustrate his lectures.