The analysis of stable carbon and nitrogen isotopes in bone collagen can reveal aspects of diet and how this may change between periods and places. Here, the authors apply a ‘whole-town’ approach to isotopic analysis, to characterise and explore variation in diet within medieval Cambridge and its hinterland. By adopting this approach, and a robust isotopic baseline, the authors argue that the number of confounding variables that typically plague archaeometric research are reduced, allowing for more nuanced interpretation of data. For medieval Cambridge, this nuance comes in the form of inter-site comparisons in the lived experience of social differentiation.