The emergence of complex society in the Maya lowlands during the first millennium BCE involved a confluence of factors including the adoption of staple maize as a major source of food, the establishment of stable sedentary communities focused on public centers, and ultimately the birth of the institution of divine kingship harnessed to a Maize God cult. In the geographic core of the Maya lowlands and in some salient areas to the north and east, this evolutionary development featured the construction of public plazas supporting architecture that has come to be known as “E Groups.” These E Groups likely served many purposes relevant to the aggregation of local populations but, in the view of the majority of contributors to this volume, they were functionally associated with solar observation and perforce calendar keeping; from their outset they were also public gathering places. E Groups are among the earliest, if not the earliest, manifestation of civic-religious public architecture in the Maya lowlands. This volume assembles a coherent set of chapters that discuss new field research results on E Groups and establish an emerging paradigmatic framework for the origins of lowland Maya civilization focused on the E Group phenomenon as a key feature of community organization and urbanism in its geographic heartland.