This MA thesis focuses on the study of pre-Columbian subsistence and dietary patterns through the use of stable carbon and nitrogen isotopic analysis of human samples (n = 20) recovered from the Acapetahua, Mazatán, and Río Naranjo zones in the Soconusco region—located in the present-day state of Chiapas, México and the Northeastern coast of Guatemala. The stable isotope results in this study demonstrate the heterogeneity of ancient human diets in the Soconusco region, illustrating the complexity of ancient people’s lifeways from the Late Archaic (3500-1900 cal. B.C.) to the Late Postclassic (A.D. 1250-1530) periods. Further, the presence of C₄ plant (i.e., maize) consumption was minor isotopically compared with the consumption of a variety of locally available wild and cultivated food resources. As a result, there is an absence of a clear subsistence transition towards maize agriculture as the main subsistence practice in the region, based on the human samples analyzed in this study. While the quantification of every food source in the diet, including maize, is more difficult without additional data and other lines of evidence, I suggest that other food products like marine, estuarine, and riverine resources, as well as other wild and cultivated plant foods may have been more important in the every-day diets of Soconusco inhabitants across time (particularly at Mazatán). This appears to have been a common pattern indicative of the wide diversity of food resources found in tropical environments across Mesoamerica.