The social and cultural origins of the Hutterian Brethren, the most inbred population in North America, are described along with the characteristics that make the group useful for genetic studies. The Hutterites represent a closed population, with high levels of fertility and consanguinity. The group maintains a stable residence pattern and keeps extensive genealogic records. The uniform pattern of communal living, the existence of endogamous subgroups within the population, and an orderly design for colony fission facilitates comparisons rarely found in other accessible populations. This inbred population is useful for detecting new recessively inherited diseases, for advancing our knowledge of the effect of inbreeding, and for analyzing human chromosomal variation. Selected demographic and genetic studies are cited.