In this paper we suggest that the spillover of knowledge may not occur automatically as typically assumed in models of endogenous growth. Rather, a mechanism is required to serve as a conduit for the spillover and commercialization of knowledge from the source creating it, to the firms actually commercializing the new ideas. In this paper, entrepreneurship is identified as one such mechanism facilitating the spillover of knowledge. Using a panel of entrepreneurship data from 18 countries, we provide empirical evidence that, in addition to measures of Research & Development and human capital, entrepreneurial activity also serves to promote economic growth.