Applying regulatory focus theory to the context of social dilemma situations, the present research demonstrates that individual differences in vigilant, prevention-focused self-regulation predict the tendency to invest private resources to punish uncooperative interaction partners (costly punishment), a behaviour that typically has strong positive effects on the collective level of cooperation. Analyses further support the distinctiveness of the vigilance system proposed in regulatory focus theory (prevention focus) in comparison with general defensive inhibitory tendencies (measured with Carver and White's Behavioral Inhibition System scale). Results document that individual differences in prevention-focused self-regulation but not differences in general defensive inhibitory tendencies are positively related to costly punishment. In sum, the findings indicate that vigilant, prevention-focused self-regulation plays a crucial role in the context of sanctions that enforce cooperation. Copyright © 2013 John Wiley & Sons, Ltd.