Northeast of modern-day Mexico City stand the remnants of one of the world's largest pre-industrial cities, Teotihuacan. Monumental in scale, Teotihuacan is organized along a three-mile-long thoroughfare, the Avenue of the Dead, that leads up to the massive Pyramid of the Moon. Lining the avenue are numerous plazas and temples, which indicate that the city once housed a large population that engaged in complex rituals and ceremonies. Although scholars have studied Teotihuacan for over a century, the precise nature of its religious and political life has remained unclear, in part because no one has yet deciphered the glyphs that may explain much about the city's organization and belief systems. In this groundbreaking book, Annabeth Headrick analyzes Teotihuacan's art and architecture, in the light of archaeological data and Mesoamerican ethnography, to propose a new model for the city's social and political organization. Challenging the view that Teotihuacan was a peaceful city in which disparate groups united in an ideology of solidarity, Headrick instead identifies three social groups that competed for political power - rulers, kin-based groups led by influential lineage heads, and military orders that each had their own animal insignia. Her findings provide the most complete evidence to date that Teotihuacan had powerful rulers who allied with the military to maintain their authority in the face of challenges by the lineage heads. Headrick's analysis also underscores the importance of warfare in Teotihuacan society and clarifies significant aspects of its ritual life, including shamanism and an annual tree-raising ceremony that commemorated the Mesoamerican creation story.