This paper explores the recent explosion in university patenting as a source of insight into the changing relationship between the university and the private sector. Before the mid-1980s, university patents were more highly cited, and were cited by more diverse patents, than a random sample of all patents. More recently several significant shifts in university patenting behavior have led to the disappearance of this difference. Thus our results suggest that between 1965 and 1988 the rate of increase of important patents from universities was much less than their overall rate of increase of patenting.

In a 1991 essay in Scientific American , Michael Porter suggested that environmental regulation may have a positive effect on the performance of domestic firms relative to their foreign competitors by stimulating domestic innovation. We examine the stylized facts regarding environmental expenditures and innovation in a panel of manufacturing industries. We find that lagged environmental compliance expenditures have a significant positive effect on R&D expenditures when we control for unobserved industry-specific effects. We find little evidence, however, that industries' inventive output (as measured by successful patent applications) is related to compliance costs.