Multiple isotopic systems (C, N, O, S, Sr, Pb) are applied to investigate diet and mobility amongst the Middle Neolithic populations at Schipluiden and Swifterbant (Netherlands). A review of carbon and nitrogen isotope analyses of European Mesolithic and Neolithic populations shows a shift in diet from the Mesolithic to the Neolithic, but also great variety in Neolithic diets, several of which incorporate fish. At Swifterbant (c. 4300–4000 BC) the population had a diet largely based on terrestrial and freshwater resources, despite proximity to tidal waters. Only one individual (of 10) showed evidence for migration. In contrast at Schipluiden (c. 3600–3400 BC) there were migrants who had a diet lower in marine resources than those without evidence for migration. The faunal spectrum and isotopic similarities with sites in the Iron Gates Gorge suggest that sturgeon may have been important. There is some evidence that migrants at Schipluiden were not accorded the formal burial given to locally born people.