The Northwestern Plains provide evidence of human occupation from Clovis times. The human groups involved were not spectacular and operated at the band level as hunters and gatherers. Changes in climate during the Altithermal Period may have caused some shifts in animal populations as a result of aridity with concomitant shifts in human occupations. The human groups were not adapted to storage of large quantities of food and as a result were operating in close harmony with the environment. Interdisciplinary efforts are needed to further resolve the past activities of human groups on the Plains.