The theory of collaborative advantage is a major theory rationalizing the role of Public-Private Partnerships (PPPs). However, the evidence for the theory in the case of PPPs is weak: the literature lacks studies that compared the actual performance and collaboration of PPPs to that of traditionally procured public projects. The aim of this article is to test the theory of a collaborative advantage of PPPs, focusing on three common performance indicators: time, cost, and perceived project performance. Data were collected on Dutch transport infrastructure projects. PPPs were compared to traditionally procured projects with non-parametric tests and robust regression using weighted least squares estimator. It was found that PPPs have better cost performance but that this performance advantage cannot be attributed to collaboration. Therefore, it is concluded that no evidence was found for the theory of a collaborative advantage of PPPs.