Large labs may spawn spin-outs caused by innovations deemed unrelated to the firm's overall business. Small labs generate demand for specialized services that lower entry costs for others. We develop a theoretical framework to study the interplay of these two localized externalities and their...

We report a puzzling pair of facts concerning the organization of science. The concentration of research output is declining at the department level but increasing at the individual level. For example, in evolutionary biology, over the period 1980 to 2000, the fraction of citation-weighted...

This paper explores the relationship between knowledge creation, entrepreneurship, and economic growth in the United States over the last 150 years. According to the “new growth theory,” investments in knowledge and human capital generate economic growth via spillovers of knowledge. But the...