ABSTRACT During the last decades a new university “mission” has been promoted from different social spheres, related with the application and exploitation, outside the academic environment, of the knowledge and other capabilities available to universities. This new mission has generated an increment of the relations between the university and its socioeconomic environment, and has opened a new field for debate and scientific analysis, focused on the conflicts and benefits of such relations. The central question that emerges in this field is if the university is the appropriate institution to transfer and to commercialize knowledge, not because this function is incompatible with the one of creating knowledge, but because it is exercised with a cost that can be excessive (David et al. 1994). It is within this context that this thesis aims to evaluate the effects that university-industry relations exercise on the development of one of the traditional university missions: research. The analysis of this question is carried out taking as case of study the University of Valencia and the Polytechnic University of Valencia. Specifically, the study sample comes from a database of more than 2,000 faculty members from these two universities, who have conducted research projects and/or been involved in UIR activities during the 1999–2004 period. The data are analyzed at lecturer level and focus on three aspects: UIR, academic research activities and scientific production. The most relevant results from this study are that UIR can have a positive effect on scientific production, depending on the type and the intensity of the linkage activity, and the partner’s characteristics. For example, if the linkage is based on activities with high scientific or technological content (R&D contracts), but only up to a certain level of intensity. These results have two important implications. On the one hand, they show that the development of routine activities for industry can result in loss of scientific production, and on the other hand, they warn of the risks of too much emphasis in UIR activities even when they are based on R&D. This highlights that, at least in this context, the condition of “more is better” does not apply to UIR activities. The above results have also important implications for the design of university policies. Although they show that UIR does not penalize per se a researcher’s scientific productivity, they underline that the indiscriminate promotion of these types of activities could result in lower scientific performance. Therefore, some policies promoting UIR as a substitute of the public funds for research, raise concerns regarding the negative impact those policies could have on scientific contribution.