From the mid-twelfth to the mid-fourteenth century, the world of the ancestral Pueblo people (Anasazi) was in transition, undergoing changes in settlement patterns and community organization that resulted in what scholars now call the Pueblo III period. This book synthesizes the archaeology of the ancestral Pueblo world during the Pueblo III period, examining twelve regions of the Anasazi world that embrace nearly the entire range of major topographic features, ecological zones, and prehistoric Puebloan settlement patterns found in the northern Southwest. Drawn from the 1990 Crow Canyon Archaeological Center conference "Pueblo Cultures in Transition," the book serves as both a data resource and a summary of ideas about prehistoric changes in Puebloan settlement and in regional interaction across nearly 150,000 square miles of the Southwest. The volume provides a compilation of settlement data for over 800 large sites occupied between A.D. 1100 and 1400 in the Southwest. These data provide new perspectives on the geographic scale of culture change in the Southwest during this period. Twelve chapters analyze the archaeological record for specific districts and provide a detailed picture of settlement size and distribution, community architecture, and population trends during the period. Additional chapters cover warfare and carrying capacity and provide overviews of change in the region. Throughout the chapters, the contributors address the unifying issues of the role of large sites in relation to smaller ones, changes in settlement patterns from the Pueblo II to Pueblo III periods, changes in community organization, and population dynamics.