The Moatfield ossuary (AkGv-65) was discovered in North York, Ontario, in 1997. Archaeological Services Inc. was contracted to exhume and then re-bury the human remains. Located on the periphery of a Late Woodland Iroquoian village, the ossuary included 87 people, 58 of them adults. First Nations authorities allowed the analysis of one tooth per person. Adult crania provided age and sex information; a posterior maxillary tooth was retained from each of 44 individuals. A single tooth proved ample to provide an AMS radiocarbon date plus stable isotope ratios. Three radiocarbon ages were measured: the site dates to ca. A.D. 1300. Stable carbon isotope ratios were measured for tooth enamel (mean d13C ¼ )4.2 1.6‰) and dentin collagen ()11.3 1.4‰Þ; the mean d15N value for dentin collagen was 12.6 0.9‰. Archaeological bone specimens (n ¼ 63) of 19 fish species from Lake Ontario provided d13C and d15N values. The results show that the Moatfield diet included selected fish species with high d15N values (lake trout, salmon, etc.) and a substantial maize component. Peak maize consumption occurred during the growth period of the 20–29-year-old age group.