Ross Hassig is a highly respected expert on the ethnohistory of the pre-Hispanic Aztecs and the early history of colonial Mexico. He is a prolific author, with books on such topics as Aztec warfare, trade, and transportation, as well as the colonial period. This is his latest book, and it again analyzes and critiques sources for the pre-Hispanic and early colonial periods, concentrating on Aztec marriage practices, how they influenced the rise of the Aztec empire, and how they were affected by Spanish domination in the colonial period. The book is an in-depth look at the practice of elite polygyny, which allowed men to have more than one wife, as it seems to have operated in the political and social organization of the Aztecs. Hassig's main point is that the effect of this polygyny on the Aztec political system and the succession of Aztec rulers, and the ways in which the Spanish managed to destabilize the system through the imposition of monogamy, has not been considered.

He begins with a brief history of the Aztec empire, including a list of rulers and the years of their rule. Women were not allowed to rule, so they tend to not appear in the sources available for the Aztec empire. Nonetheless, they turn out to be key to understanding the political history. Hassig considers Aztec marriage patterns based largely on the early Spanish sources, which always require careful interpretation because these early chroniclers were describing a society and culture very different from their own. Nonetheless, they made it clear, as is common in many societies, that polygyny was practiced mainly by the noble and wealthy. Hassig looks at the demographic and social consequences of polygyny versus monogamy, as collected from more recent ethnographic and historical sources.

This introductory material leads to the important chapter on “Reassessing the Aztec Kings,” wherein Hassig examines the information on the Aztec king list and considers how kinship based on polygyny influenced the process of determining successors. Most rulers were chosen from among possible candidates, who might be other than the eldest son of the previous ruler. Polygyny allowed males to make alliances with other royal or noble lines to ensure they would have well-connected cohorts of sons. Hassig's contribution is a new model that shows how these cohorts worked in determining succession and why rulers fall into related clusters. These clusters change as cohorts age and diminish in influence and a collateral cohort reaches its prime and selects a successor.

Royal polygyny allowed the rise and expansion of the Aztec empire, as marriages could consolidate alliances and conquests. Polygyny is also used to explain the social mobility present in Tenochtitlan, which could be upward for women marrying into the noble class or downward for nobles who might fall back into the commoner class. Hassig wants to illustrate how previously inattention to kinship and marriage patterns has impeded understanding of Aztec politics and society. Also, the importance of Aztec women, both nobles and commoners, has been underestimated because of the lack of attention to their importance in marriage.

Hassig is also concerned with the role polygyny played in the Spanish conquest and the consolidation of Spanish domination in Tenochtitlan, and ultimately all of Mexico. While the importance of new diseases and demographic loss in the aftermath of conquest are not to be denied as destructive forces, the disturbance of normal marriage patterns and the alliances cemented as a result caused political instability that interfered with determining succession and stabilizing rule. Also, the imposition of monogamy with its smaller families and inheritance by primogeniture undermined Aztec society and consolidated the Spanish family pattern. Hassig has presented evidence that the study of kinship and marriage patterns is crucial in understanding the Aztecs and other complex societies, a further important contribution from this researcher.