Stable isotopic analysis of carbon and nitrogen from human skeletal remains has been conducted at multiple Maya archaeological sites from the lowlands of Belize, the Peten, the Yucatán peninsula, and the highlands of Guatemala. The first applications of this practice were conducted on the remains found in the Tehuacan Valley and suggest that maize was a dietary staple as early at 4500 BP. However, the bulk of information is represented by over 600 individuals dating from the Preclassic to the Postclassic period and substantiates that subsistence adaptations were present and caused by chronology, geographic and environmental factors, and cultural pressures.