Compares archaeological and isotopic characterizations of diet, specifically the role of maize, for Woodland, Mississippian, and Oneota populations from the North American midcontinent. Presents newly generated delta¹³C values for five sites from the central Mississippi and Illinois river regions. Archaeological and isotopic evidence for maize-dependence is evaluated for biases that may underlie the seeming contradictory diachronic and synchronic patterning evident in the two data sets.