["International Journal of Osteoarchaeology, EarlyView. ", "\nABSTRACT\nStudying goose domestication through archaeological finds has been challenging due to the similar skeletal morphology of the European domestic goose and its wild progenitor, the greylag goose (Anser anser). We analyzed stable carbon (δ13C) and nitrogen (δ15N) isotopes from bone collagen of subfossil domestic and potentially domestic geese to investigate dietary differences indicative of domestication. These samples were previously analyzed for mitochondrial DNA (mtDNA), which can distinguish between wild greylag geese and their domestic form, although some specimens exhibited atypical mtDNA haplotypes or haplotypes belonging to other wild Anser species. We also verified the chronological age of the bones through radiocarbon dating, which yielded dates ranging from the Medieval to Postmedieval periods (600–1600 ce). We revealed that some Russian domestic geese were probably supplementary fed with fodder fertilized with animal manure, while others were allowed to free‐roam, indicating variable goose management practices in the Middle Volga region. Some of the geese exhibited high δ15N values, which may indicate the inclusion of animal protein in the diet, and one goose showed evidence of marine components or consumption of either C4‐plants growing in arid or saline habitats or manure‐fertilized agricultural C4 plants. Stable isotope analysis was informative regarding supplementary feeding, but could not reliably determine wild or domestic status, as some genetically domestic geese exhibited low δ15N values, suggesting a wild‐like diet. Therefore, the domestic or wild status of specimens with taiga bean goose mtDNA remains unresolved. Tamed wild geese also present a limitation to this method, as they may receive the same diet as domestic geese.\n"]