Few areas in economics enjoy better theoretical grounds than Industrial Organization. And David Austretsch has greatly contributed to improve the IO field with his own dynamic models of entrepreneurship and, also, the inspiration and stimulus he has instilled to other scholars. In his article published in this issue Audretsch discusses two main concepts: one is the model of the filter of knowledge; the other is the idea of entrepreneurship capital. The concept of filter of knowledge is central to the present discussion about the links between scientific and technological knowledge generation and its effective rate of transfer to market innovation. It shows why and how those agents that generate knowledge are seldom the same that get to commercialize it. The bridge is often an entrepreneur. The second idea, here highlighted, about entrepreneurship capital has become in some way very popular thanks the publication of many reports on rates of firm creation. In this case, although the theoretical concept is worth developing, the empirical application of the model has proven to be difficult and ambiguous until now.