Classic sociological solutions to cooperation problems were rooted in the moral judgments group members make about one another's behaviors, but more recent research on prosocial behaviors has largely ignored this foundational work. Here, we extend theoretical accounts of the social effect of moral judgments. Where scholars have emphasized the roles of moral judgments in clarifying moral boundaries and punishing deviants, we present two less intuitive paths from moral judgments to social behavior. We argue that those who engage in moral judgments subsequently act more morally. Further, we argue that group members anticipate the more moral behavior of judges, trusting them more under situations of risk and uncertainty. We thus establish paths from moral judgments to the primary foundations of voluntary cooperation: trust and trustworthiness. The results of three experiments support the predicted effects: Participants randomly assigned to make moral judgments were more trustworthy in subsequent interactions (Study 1). A follow-up experiment sought to clarify the underlying mechanism, showing that making moral judgments led individuals to view themselves as more moral (Study 2). Finally, audience members anticipated the greater trustworthiness of moral judges (Study 3).