Two studies examined narcissism and behavior in a commons dilemma. Study 1 used a four-person, laboratory-based task and Study 2 used a dyadic task. Participants were told that they represented one of four (Study 1) or two (Study 2) forestry companies and then were asked to harvest timber from a renewable forest. Narcissism was found to be positively related to acquisitive goals and harvesting more timber in the initial round. The more narcissists harvesting in the competitive group of four (Study 1) or dyad (Study 2), the less timber was harvested overall and the more rapidly the forest was depleted. Within competitive groups and dyads, however, narcissists harvested more than the nonnarcissists competing with them. In all, narcissism provided a benefit to the self, but at a long-term cost to other individuals and to the commons.