The outsourcing of R&D activities is considered an important way to acquire external technological information that can be integrated into a firm’s own knowledge endowment. Given the complex relationship between R&D partnerships and innovation performance, it becomes of paramount importance for scholars, managers and policy-makers to understand whether and how outsourcing benefits the firm. This paper tries to assess the impact that external sources of R&D may have on product innovation, differentiating between R&D supplied by universities and other companies. The empirical analysis is based on a large and representative sample of European manufacturing companies. The analysis considers R&D an endogenous decision in investigating its effect on product innovation. An instrumental variable two-step estimation method is employed to deal with this issue. The results suggest that R&D intensity, or the share of R&D acquired from external sources, has a positive and significant effect on product innovation. Furthermore, we find evidence of an inverse U-shaped relationship between R&D outsourcing and innovation, meaning that on average, costs start to outweigh benefits as the R&D collaboration projects increase. We also estimate high returns from R&D acquired from universities on the probability to achieve product innovations, while having firms in the same group as research partners has the largest effect on innovative product sales. The results have straightforward implications for the practice of R&D managers. In order to gain advantages from partnership in research, innovation managers need to jointly exploit these different types of collaboration activities and their potential synergies. Given that the innovative firms in the sample desire additional credit which actually they do not obtain, R&D managers should also be concerned with the financing sources firms have access to. Finally, the analysis suggests that managers ought to identify the appropriate level of external acquisition in order to fully benefit on innovation.