The division of society and space into halves or “moieties” has been an important feature of Andean culture for centuries. Contemporary moieties are often regarded as the result of either an impervious pre-Columbian conceptual model that has resisted Spanish influence or of marriage preferences. In this article I challenge these views, arguing that the ubiquity of moiety organization today can best be understood as the result of an indigenous imperial model of domination, the extractive uses of which continued into the Spanish Colonial and Republican periods. Based on a case study from the southern Peruvian Andes, I demonstrate that the continued use of moieties in Andean communities must also be understood in terms of the role that dualism plays in ritual action and other conceptual and social domains. I also explore the relationship between equilibrium and extractive ideologies, and between historical models and contemporary social process.