Spiro Mounds was a ceremonial complex located on the Arkansas River, situated in a natural corridor between the Southeast, the Plains, and the Southwestern United States. Considered a quintessential Mississippian site (ad 1000–ad 1450), Spiro was strategically placed as a cultural gateway. Here, dental evidence is presented to aid in the determination of dietary regime and overall population health. The hypothesis regarding the delayed transition to maize agriculture in the Arkansas River Valley will be tested through population comparisons of dental remains. This study will expand the bioarchaeological investigation of a region that has had limited systematic examination. Statistical analysis showed a significant difference between Alluvial, Upland, and Plains environmental zones, and the pattern of dental pathology. Assaults on the dentition at Spiro are moderate. Caries and hypoplasia rates fall just under but approaching those expected for agricultural populations (57% and 49%, respectively). The high number of occlusal caries indicates slower cariogenic destruction and a slower attrition rate. Ante mortem tooth loss was low (18%), with moderate dental attrition (61%). The dental analysis of Spiro Mounds reveals a population with little generalised stress resulting from environmental or sociocultural influences. Comparisons of Spiro to other larger sites in the Mississippian sphere is revealing regarding widespread cultural traditions and their affect on population health; Spiro's unique circumstances give evidence of a population in transition to maize agriculture, but not fully committed to it. Higher status individuals were slower to change from the subsistence strategies that had made them biologically successful. Recent isotope data support this conclusion. The delayed role of maize agriculture at Spiro Mounds, as well as its ideal location within the Mississippian sphere, indicates a different social evolution than other influential Mississippian centres. Copyright © 2015 John Wiley & Sons, Ltd.