We present a model that separates entrepreneurship from profit-motivated corporate R&D aimed at improving existing production processes. Our model embeds the core idea of the knowledge spillover theory of entrepreneurship in established knowledge-based growth models by enriching their knowledge spillover structure. Introducing knowledge spillovers drives a wedge between the optimal and market allocation of resources between new knowledge creation and commercialization. We show the first best allocation depends exclusively on the relative strength of knowledge spillovers between them and derive propositions to guide policy that can bring the market equilibrium closer to this optimum