This paper is among the first to investigate the impact of over-education and over-skilling on workers' wages using a unique pan-European database covering twenty-eight countries for the year 2014, namely the CEDEFOP's European Skills and Jobs (ESJ) survey. Overall, the results suggest the existence of a wage penalty associated with over-education. When the educational and the skills mismatches are interacted with each other in order to distinguish apparent over-education from genuine over-education, the results highlight that the workers with the highest wage penalty are those who are both over-educated and over-skilled.