The EU infrastructure policy has relied on Public-Private Partnerships (PPPs) as a means to successfully deliver infrastructure of benefit for the EU. To reach its infrastructure policy objectives, the EU has implemented support mechanisms aimed at facilitating the delivery of PPPs. This article is aimed at evaluating to what extent these mechanisms have actually contributed to improving the economic performance of PPPs. To that end, we have selected the case of Spanish road PPPs for empirical analysis. The main result shows that EU support positively influences the economic performance of PPP projects. This is caused by the fact that the EU conditions its financial support on a project’s meeting a set of requirements that help assure the success of the project. From this result, we obtain a set of conclusions that may be generalised to other cases, and provide a contribution to the body of knowledge on PPPs.