This study integrates isotopic, palaeopathological, and historical evidence to investigate infant and young child feeding practices in a Roman period (1st to 3rd centuries AD) skeletal sample from the Isola Sacra necropolis (Rome, Italy). Stable isotope analysis of bone collagen from 37 rib samples indicates that transitional feeding began by the end of the first year and weaning occurred by 2–2.5 years of age. Both δ15N and δ13C data clearly show the trophic level effect associated with breastfeeding. Childhood diet is investigated using dental pathology data in the deciduous dentitions of 78 individuals aged between 1 and 12 years. The presence of calculus, caries, and tooth wear in young children suggests that individuals were provided complementary foods and other items that impacted their dental health at an early age. The isotopic and dental data are generally consistent with the historical evidence from the Roman period with respect to the general timetable of weaning and the character of complementary foods. This is the first study to integrate isotopic and deciduous dental pathology data to explore infant and young child feeding practices in the Roman world. Am J Phys Anthropol 2008. © 2008 Wiley-Liss, Inc.