As complex societies emerged in the Maya lowlands during the first millennium BCE, so did stable communities focused around public squares and the worship of a divine ruler tied to a Maize God cult. "E Groups," central to many of these settlements, are architectural complexes: typically, a long platform supporting three structures and facing a western pyramid across a formal plaza. Aligned with the movements of the sun, E Groups have long been interpreted as giant calendrical devices crucial to the rise of Maya civilization. This volume presents new archaeological data to reveal that E Groups were constructed earlier than previously thought. In fact, they are the earliest identifiable architectural plan at many Maya settlements. More than just astronomical observatories or calendars, E Groups were a key element of community organization, urbanism, and identity in the heart of the Maya lowlands. They served as gathering places for emerging communities and centers of ritual; they were the very first civic-religious public architecture in the Maya lowlands. Investigating a wide variety of E Group sitesincluding some of the most famous like the Mundo Perdido in Tikal and the hitherto little known complex at Chan, as well as others in Ceibal, El Palmar, Cival, Calakmul, Caracol, Xunantunich, Yaxnohcah, Yaxuna, and San Bartolothis volume pieces together the development of social and political complexity in ancient Maya civilization.