The Plateau culture area of northwestern North America fits the criter
ia of an interaction sphere. Understanding the general cultural dynami
cs responsible for the creation of interaction spheres has been poorly
developed in archaeological and ethnological theory. Data from the Pl
ateau Interaction Sphere are used to argue that the main factor respon
sible for the emergence of interaction spheres in transegalitarian soc
ieties is the development of an elite class. Elites who seek to maximi
ze their power and wealth at the tribal level do so in part by establi
shing trading, marriage, ideological, military, and other ties to elit
es in other communities and regions. They use these ties to monopolize
access to desirable regional prestige goods and to enhance their own
socioeconomic positions. In conformity with expectations derived from
this model, the data from the Plateau demonstrate that interaction sph
ere goods are predominantly prestige items and that these concentrate
in communities that have the greatest potential to produce surplus and
to develop socioeconomic inequalities. These same features also seem
to characterize well-known interaction spheres elsewhere in the world.