Stable carbon and nitrogen isotope results are presented for a sample of human and faunal bones and food remains excavated from Pompeii. The well-preserved organic remains provide a valuable resource to examine ancient lifeways associated with a Roman city during a distinct period of time associated with the eruption of Vesuvius in AD 79. Isotopic results indicate human diets that are consistent with the archaeological and documentary evidence for diverse dietary intake for all residents of Pompeii consisting of a range of cereals, fruits, vegetables, seafood, and meat from domestic and wild animals. Males had similar animal protein intakes to those of females, but they ingested significantly greater amounts of seafood than females. The great range of dietary variability among and between males and females indicated by the isotopic data suggests the existence of past dietary distinctions based on social role and/or social class. In comparison to other isotopic studies in the region, human diets at Pompeii are similar to those of Danish farmers and coastal Greek colonies in southern Italy (Metaponto) but included greater amounts of marine protein. Carbon isotope values for domestic animals indicate a C3-based terrestrial diet, while nitrogen isotope values distinguish herbivores from omnivores and carnivores.