The North American Southwest extends from southeastern Utah and southwestern Colorado into Chihuahua and Sonora, and from central New Mexico to the Grand Canyon and the lower Colorado River (Fig. 1). As delineated, this geographically heterogeneous area is united by an arid to semiarid climate, a condition that has had major impact on cultural manifestations. The archaeological record extends some 11,000 years and encompasses ways of life characterized by highly mobile hunting and gathering, semisedentary and sedentary horticulture, and following the introduction of domestic livestock by Europeans, economies of mixed herding and horticulture. The diversity of lifeways pursued over time, and at anyone time, has led anthropologists to debate whether the Southwest is best described as a single culture area, as more than one culture area, or as a regional zone of cultural interaction (see Daifuku 1952; Kirchoff 1954; Kroeber 1939; Martin and Rinaldo 1951). Some scholars have employed a variety of trait lists in suppon of the general cultural unity of the Southwest (see Jennings and Reed 1956; Rouse 1962). We also favor emphasizing the essential unity of the Southwest, although our view focuses on the dynamics of cultural interactions over time in the area. The unity is reflected in the consistent sychroneity of changes described in the framework of southwestern culture history that emerged from the conference and is described below. This framework also indicates that the greatest similarities in the material remains of the archaeological record of the area occur at the start of the time period under consideration, a time when both horticulture and sedentism began to set the Southwest apart from two adjacent regions-the Great Plains and the Great Basin-where hunting and gathering continued to be the primary mode of subsistence. Despite increased regional variation over time in the Southwest. The complex and changing web of cultural interactions within the area becomes a hallmark of its unity and overshadows interactions with neighboring regions. The Southwest enjoys a unique position in American archaeology. Due to the exceptional preservation of archaeological remains. The unmatched predsion of temporal control and palaeoenvironmental data for the prehistoricperiods. and the continued existence in the area of vital American Indian cultures. The Southwest is often seen as a natural laboratory appropriate for evaluating archaeological method and theories of cultural development and change. With the recent phenomenal growth of public archaeology in the western United States. The pace and scale of southwestern archaeological research has greatly accelerated. The vast quantity of literature of the 1970s and 1980s is difficult for even area spedalists to control. Boththe general interest in the prehistory of the Southwest and the avalanche of recent infonnation suggested to the conference partidpants that this volume would be of interest to a broad community of scholars. The Southwest has long been known for its archaeological conferences.The first. and still most famous, was the Pecos Conference of 1927. A. V. Kidder invited scholars to Pecos Pueblo in order to devise a scheme that would reflect the broad outlines of all southwestern prehistoric development. and to resolve issues of nomenclature and terminology (Kidder 1927). The Pecos Conference is now an annual event held at the end of the summer field season. and therefore serves primarily as a forum for discussion of current fieldwork with some topically oriented sessions. In additionto the Pecos Conference with its pan-southwestern focus. The recent volume of data recovery has been so great that there are now biannual conferences devoted to the Mogollon (e.g ., Benson and Upham 1986). Hohokam (e.g ., Dittert and Dove 1985a. 1985b) and the Anasazi (e.g ., Smith 1983). In January of 1988. The first. in what may become a regularly scheduled pansouthwesternconference devoted to topical syntheses. was held in Tempe, Arizona. Over the past decade. there have also been topically oriented conferences that have brought together spedalists from diverse disdplines in order to address a particular problem area. These have included conferences aimed at developing detailed palaeoenvironmental reconstructions and relating these to prehistoric settlement and technological changes (e.g ., Dean et al. 1985; Gumennan 1988) and conferences on specific topics in cultural resource management (e.g ., Cordell and Green 1983; Green and Plog 1983; Plog and Wait 1982). Of a slightly different nature are conferences that bring southwestern archaeologiSts together to address broader thematic issues. The 1955 Seminars in Archaeology (Jennings and Reed 1956) focused on deter mining the extra-southwestern origins of various southwestern, culture traits. The School of American Research seminar on prehistoric Pueblo social organization (Longacre 1970) was more restricted geographically, examining only those southwestern societies that could be construed as Pueblo. The seminar grew out of early processual archaeology in the attempt to reconstruct nonmaterialaspects of prehistoric culture and had an impact far beyond the scholarship of the Southwest. The aims of the current seminar were, in some respects, broader than either the 1955 seminar or the seminar on prehistoric social organization. The conference was concerned, first, with synthesizing the culture history of key regions of the Southwest and, second, with describing and explaining .underlying patterns of stability and change among the prehistoric cultures represented. In papers prepared for the seminar, participants were asked to provide background on the environment and paleoenvironment of their areas, review the culture history of their areas, and discuss the dynamics behind that culture history. As might be expected, considerable seminar time was spent learning the details of the sequences presented. Nevertheless, the seminar produced two worthwhile results: first, a framework with descriptive nomenclature relating to synchronous periods of stability and change, and second, discussions of cultural dynamics pertinent to periods ofapparent isolation and interaction among local areas within the Southwest. The patterns of interaction and isolation described during the conference were diverse. For example, a pattern such as the synchronous appearance of a distinctive ceramic style might suggest interaction that could have been the result of trade, migration, or the political ascendancy of a group whose pottery other cultures replicated. On the other hand, a pattern such as a synchronous shift in settlement distribution might be the result of purely local responses to a regional climatic event. There are also examples of times when distinctive stylistic features were restricted to local areas. These were generally interpreted as reflecting cultural isolation. After reviewing the local culture histories, much conference time was spent discussing the processes underlying similarities among the areas that seemed to indicate cultural interaction. It was in conceptualizing, describing, and discussing possible forms of political, social, and religious interactions that there was the most diversity in the vocabulary of the participants. Some used the term "alliances," some "interaction spheres," and some just the term "systern." In part, the diversity reflects controversy over the nature of the interactions, and in part just the novelty in approaching these questions. Over the past ten years, southwesternists have moved far from developing the culture histories of single river valleys into discussions of a broadly regional nature. Yet, there is still uncertainty about the way in which regional phenomena should be described. One area of conference discussion involved attributing some of the evidence for interaction to the effects socially complex systems had on broad areas of the Southwest. Traditionally, the prehistoric Southwest has been considered an area that supported only egalitarian societies. Recently, there hasbeen a great deal of discussion about systems that were socially hierarchical. While many investigators continue to be leery of ascribing hierarchical orsanization to any prehistoric southwestern group, most of the seminar participants acknowledged that at least a few of the prehistoric systems,notably those centered at Chaco Canyon, Casas Grandes, and the Hohokam region, influenced areas well beyond their own borders. Their degree of influence suggests organizational complexity beyond that of egalitarian groups as generally defined. There is continued disagreement among those participating in the conference (and probably among southwestern archaeologists in general) about the degree of social complexity involved. Here we find Gregory Johnson's (this volume) observations and discussion most useful. Johnson's background in studying social hierarchies theoretically and in the early civilizations of the Near East allows us to see that in comparison to the early complex societies of the Old World, the southwestern examples are simple and modular. A key element in this simplicity is the lack of obvious economic stratification in the Southwest that, in tum, is a reflection of the relatively low levelof environmental productivity. From our perspective, the limitations of the southwestern environment and fluctuations in climate are crucial components in understanding prehistoric change. This is an issue we address in some detail below. We also believe that we need to develop broader and more innovative approaches to finding appropriate ethnographic analogs for the prehistoric societies of interest. © 2006 by The University of Alabama Press. All rights reserved.