This paper analyses country-specific determinants of knowledge flows with a view to uncover the role of cross-organizational interactions. Using a sample of some 600,000 patents from the EU27 member states in the period 1990–2007, we take backward citations as dependent variable and find that technological sophistication and research size have a positive effect on knowledge flows. While a national bias towards applied research and development has a negative impact, individual public–private cooperation has a moderating effect due to the generation of scientific knowledge by public institutions. The present study contributes to the debate concerning the direction of R&D investments and provides empirical support to policies aimed at the enhancement of public–private cooperation.