Environmental conditions clearly influenced the cultural development of societies in the Intermountain West, but how did interactions with neighbors living along the region’s borders affect a society’s growth and advancement, its cultural integrity, and its long-term survival? Relationships among different societies are, of course, crucial to the spread of information, innovation, and belief systems; to the maintenance of exchange and mating networks; and to the forging of ethnic identity. In these ways and others, intergroup relationships can be as strong a force in shaping a society’s identity and future as are local social and economic dynamics. Meeting at the Margins focuses on the ways in which different societies in the Intermountain West profoundly influenced each other’s histories throughout the more than fourteen millennia of prehistoric occupation. Historically, inhabitants of this region frequently interacted with more than forty different groups-neighbors who spoke some two dozen different languages and maintained diverse economies. The contributors to this volume demonstrate that in the prehistoric Intermountain West, as elsewhere throughout the world, intergroup interactions were pivotal for the dynamic processes of cultural cohesion, differentiation, and change, and they affirm the value of a long-term, large-scale view of prehistory.