ABSTRACTThe long-run relationship between R&D and regional knowledge: the case of France, Germany, Italy and Spain. Regional Studies. This paper incorporates time dependence into a regional knowledge-production function framework. Within this setup, the long-run dynamic behaviour of research and development (R&D) and knowledge is analysed in four European countries – France, Germany, Italy and Spain – using unit-root tests and co-integration techniques. We find that the regional stock of knowledge is co-integrated with R&D employment and external knowledge. Nonetheless, knowledge spillovers play a more important role in the generation and accumulation of new ideas. This suggests that innovation policies should aim at enhancing knowledge diffusion and regional absorptive capacity.