Explaining human cooperation is a long-standing challenge in both social and biological sciences. Recent research has shown that altruistic punishment provides a solution to this intriguing puzzle. Altruistic punishment means that individuals punish non-cooperators, even if punishment is costly and yields no apparent benefits for the punishers themselves. However, why would people incur costs to punish non-cooperators and thereby provide benefits to others? In the proposed research we argue that emotions are the underlying mechanism for costly punishment. More specifically, we argue that anger and satisfaction work in concert to provide the motivation necessary for people to costly punish noncooperators.