Public participation in decision making has been widely advocated by scholars and practitioners as a remedy for public resistance against sustainable energy projects. Yet, it is unclear via which processes public participation in decision making may affect public acceptability of energy projects. We hypothesize that public participation in decision making is likely to increase project acceptability when it enhances perceived procedural fairness. Moreover, we hypothesize that perceived procedural fairness is higher when people can participate and influence major rather than only minor aspects of the project. We conducted three experimental studies in the Netherlands to test these hypotheses, with renewable energy projects as a case in point. As expected, public participation in decision making increased perceived procedural fairness, particularly when people could influence major aspects of the project. In turn, higher perceived procedural fairness enhanced public acceptability of the projects. Interestingly, when controlling for perceived procedural fairness, public participation in decision making had no effect (Study 2) and even a negative effect (Study 1 and 3) on project acceptability, particularly when people could influence major aspects. We conclude that public participation in decision making can enhance project acceptability if people can influence major aspects and perceive the decision making as fair. Next, our findings point out that there may be other processes instigated by public participation in decision making that can influence project acceptability. We discuss the theoretical and practical implications of our findings.