This essay analyzes critically the idea of knowledge spillovers, especially as it enters the New Growth Theory. The conventional theory of spillovers, we argue, suffers from a thin and misleading account of the nature of productive knowledge. In this model, firms undersupply R&D, which impedes...

In this survey, we examine the operations of innovation processes within industrial districts by exploring the ways in which differentiation, specialization, and integration affect the generation, diffusion, and use of new knowledge in such districts. We begin with an analysis of the importance...