No one who has seen the fortified villages and inaccessible cliff dwellings of the Pueblo III period of Anasazi culture can fail to have been impressed by the amount of labor expended in their construction or by the inconvenience entailed in living in them. It is clear that they reflect an urgent need for defense; it is less clear against whom their builders had to defend themselves. Southwestern archaeologists have been prone to dismiss this problem with somewhat vague statements about nomad invasions which compelled the agricultural Anasazi to draw together into large groups and build strongholds. This theory was a dyanced very early in the history of Southwestern research, when most of our present information on this region was lacking, and it may be profitable to re-examine it at this time.