Social dilemmas occur when individual desires clash with group needs. How can people be encouraged to cooperate when they have reason not to? In a new Nature paper, Hilbe and Krishnendu Chatterjee of the Institute of Science and Technology Austria (IST Austria), together with Martin Nowak of Harvard and Stepan Simsa of Charles University, have shown that if the social dilemma that individuals face is dependent on whether or not they work together, cooperation can triumph. This finding was the result of a new type of framework that they introduced—one that extends the entire theory of repeated games. Moreover, as their work pinpoints the ideal conditions for fostering cooperation, they have provided tools to systematically build cooperation.