The ethnographic collections of the Field Museum of Natural History contain 163 objects collected among the Assiniboine and Yanktonai Sioux by George Dorsey in 1900. Small collections were made for the World's Columbian Exposition by E. F. Wilson and Edward Ayer. The artifacts in these collections are described and illustrated. For comparative purposes, information is included from previous studies of the Assiniboine, Yanktonai, and neighboring peoples on the northern Plains.