We address the general problem of sociopolitical evolution in highland Peru during the Late Intermediate period (ca. A.D. 1000-1470) from the perspective of changing relationships between herders and cultivators in the Tarama-Chinchaycocha region. First, we use ethnographic and ethnohistoric information to help model central Andean herder-cultivator interaction. Here we emphasize the ecological and sociological foundations for economic specialization, the ritually based integration of pastoral and agricultural groups in the absence of strong state organization, and how the ritually interactive units define and maintain their borders. Second, in the light of these perspectives, we examine archaeological settlement pattern data from our study area in the central highlands of Peru. We conclude that the Late Intermediate period was a time of significant organizational change that included new forms of ritually based local and regional integration of pastoral and agricultural economies. Third, we briefly consider the general implications of our findings for understanding organizational change throughout the central Andean highlands during the Late Intermediate period. We suggest that the largest and most complex Late Intermediate highland polities depended on the full integration of specialized pastoralists and agriculturalists in those regions where both economies could attain maximal combined productivity in the aftermath of the breakdown of large states at the end of the Middle Horizon (ca. A.D. 600-1000).