We examined whether neural responses associated with judgments of socially relevant aspects of the human face extend to stimuli that acquire their significance through learning in a meaningful interactive context, specifically reciprocal cooperation. During fMRI, subjects made gender judgments on faces of people who had been introduced as fair (cooperators) or unfair (defector) players through repeated play of a sequential Prisoner's Dilemma game. To manipulate moral responsibility, players were introduced as either intentional or nonintentional agents. Our behavioral (likebility ratings and memory performance) as well as our imaging data confirm the saliency of social fairness for human interactions. Relative to neutral faces, faces of intentional cooperators engendered increased activity in left amygdala, bilateral insula, fusiform gyrus, STS, and reward-related areas. Our data indicate that rapid learning regarding the moral status of others is expressed in altered neural activity within a system associated with social cognition.