Cooperation in 2-person social dilemmas was examined when people frame outcomes as gains or as losses. It was argued that losses loom larger than gains and that depending on people's social motive, behavioral options in social dilemmas are valued differently. Results of 3 experiments supported the predictions based on prospect theory and interdependence theory: Pro-socials (cooperators) cooperated more in a loss than in a gain frame, whereas individualists cooperated less in a loss than in a gain frame. Unexpectedly, competitors cooperated as little in a loss as in a gain frame, which was attributed to a floor effect. It was concluded that this research explains inconsistent findings from previous research on gain-loss frames and shows that loss-framed individuals pursue their cooperative or individualistic goals to a greater extent than gain-framed individuals but pursue their competitive goals to about the same extent.