To adapt one’s behavior to suit changing social contingencies, it is necessary to be skillful at detecting such changing contingencies in the first place. As a consequence, the ability to detect changing contingencies (reversal learning) should predict social competence across both competitive and cooperative social settings. Consistent with this possibility, Study 1 revealed that better reversal learning predicted more effective conflict management and partner happiness within romantic relationships. Studies 2a and 2b found that better reversal learning predicted less satisfied negotiation partners, an effect mediated by the positive relationship between reversal-learning performance and value gained from the negotiation. In Study 3, better reversal learning predicted greater partner cooperation and more favorable outcomes in a multi-round prisoners’ dilemma game. These results suggest that the capacity to detect changing contingencies, and thereby modify one’s behavior in response to a socially dynamic world, facilitates interpersonal competence across a variety of social domains.