In 1910, the Eugenics Record Office was founded in Cold Spring Harbor, New York, as a center for the study of human heredity and a repository for genetic data on human traits. It merged with the Station for Experimental Evolution in 1920 to become the Department of Genetics at the Carnegie Institution, and under the direction of Charles B. Davenport and later of Albert Blakeslee and Milislav Demerec, it became the most important center for eugenic research in the nation. However with intellectual currents shifting, the Carnegie Institution stopped funding the office in 1939. It remained active until 1944, when its records were transferred to the Charles Fremont Dight Institute for the Promotion of Human Genetics at the University of Minnesota. When the Dight closed in 1991, the genealogical material was filmed by the Genealogical Society of Utah and given to the Center for Human Genetics; the non-genealogical material was not filmed and was given to the American Philosophical Society Library. Following the original order, the ERO Records are organized into thirteen series: I. Trait Files, 1670-1964 ; II. Trait Card Boxes, 1904-1939 ; III. Family Traits Card Boxes, 1920-1939 ; IV. RFT Submitters Card Catalog, 1910s-1930s ; V. Record of Family Traits, 1911-1940 ; VI. Fitter Family Studies, 1913-1936 ; VII. Field Worker Files, 1911-1926 ; VIII. Volunteer Collaborators, 1912-1939 ; IX. Pedigrees, 1828-1926 ; X. Harry H. Laughlin Files, 1915-1938 ; XI. Bibliographia Eugenica, 1734-1934 ; XII. Midget Schedules, 1919-1964 ; XIII. Index Card Boxes, 1910s-1930s.

The papers contain correspondence, research and teaching notes, data (card and slip) files, published and unpublished manuscripts by Lounsbury and others, books and reprints, sound recordings, and computer programs and files. Correspondents include: William N. Fenton, Mary R. Haas, William C. Sturtevant, Morris Swadesh, and Carl F. Voegelin. Roughly one-quarter of the collection relates to Iroquoian languages and includes much WPA Oneida Project material. Research into the Cherokee language, South American languages, and kinship structures is also well represented. Floyd Lounsbury's wife, Masako Yokoyama Lounsbury, is represented by a smaller amount of material relating to linguistic research in Shanghai and research on Quechua.