An ongoing question is whether private (religious) schools provide better education than public schools. This study re- addresses this issue, using PISA 2006 and 2009 data for the Netherlands and three different methodologies. Overall, there is no consistent pattern. Results based on ordinary least squares and propensity score matching suggest private school attendance is positively associated with mathematics achievement, but only for PISA 2006. Instead, the results generated by an instrumental variable approach are very unstable. A thorough understanding of selection processes in Dutch education, and better data, seem necessary for future empirical work on this matter.