Urban environments provide novel resources for urban wildlife. The diets of urban-living animals often shift in response to resource availability, with cascading impacts on population health and behavior, ecosystem processes, and human-wildlife conflict. To better understand how urbanization alters the diet of wildlife, we compared the diets of an urban and non-urban population of coyotes (Canis latrans) using stable isotope analysis. We measured δ13C and δ15N of coyote vibrissae from 48 individual coyotes from San Francisco (urban) and Marin (non-urban) counties. We compared δ13C, a proxy for anthropogenic food consumption, and δ15N, a measure of protein assimilation, between the two populations. We also compared the isotopic dietary niche breadths between the two populations. By comparing the diets of urban and non-urban coyote populations, we shed light on how diet composition and breadth are altered by urbanization. Further investigation of the physiological effects of altered urban diets is needed to refine understanding of how urban environments impact wildlife.