With National Science Foundation support Dr. Robert Hard and his colleagues will conduct three seasons of archaeological research at the site of Cerro Juanaquena, located in northwestern Chihuahua, Mexico. The site covers over 8 hectares and includes over 8 km of terraces and walls. The investigator estimates that ca. 20,000 metric tons of material were moved during its construction. During NSF supported preliminary research at the site, the team confirmed the site's placement, based on artifact typology, within the Late Archaic period. Radiocarbon determinations yielded an age of ca. 3070 years before the present. This makes the site extremely important because it shows that it precedes by 1500 years other northern Mexican sites of similar size and labor investment. At that time maize, an important staple in Middle America was just beginning to spread widely and most peoples still lived by hunting and gathering. It is extremely unusual for sites at this level of complexity to develop on a non-maize subsistence base. Paleobotanical analysis of collected samples shows that maize in fact is present, but it is relatively unimportant ranking lower in importance than many native plants, including cheno-ams, lovegras, chia, milkvetch and wild gourd. These findings contradict the archaeological expectation that the intensive occupation and major labor investment at Cerro Juanaquena were based on maize agriculture. Heavily worn grinding stones are common at the site and it appears that wild seeds played a central dietary role. Dr. Hard and his colleagues will now conduct extensive excavation at the site. Approximately thirty terrace features will be excavated in order to gauge the occupation span. The level of sedentism at the site and its history will be determined through examination of the organization and planning of terrace constructions. A major flotation program will be initiated to recover seeds and other plant remains, and these together with abundant fauna will shed additional light on subsistence practices. Cerro Juanaquena is unique and its existence has caused archaeologists to reevaluate their understanding of the initial spread of agriculture and related models of sedentism and village development. These issues are of relevance not only in Mesoamerica but in other parts of the world where domestication of plants and animals independently occurred.