Do followers perform better when their leader expresses anger or when their leader expresses happiness? We propose that this depends on the follower's level of agreeableness. Anger is associated with hostility and conflict-states that are at odds with agreeable individuals' goals. Happiness facilitates affiliation and positive relations-states that are in line with agreeable individuals' goals. Accordingly, the two studies we conducted showed that agreeableness moderates the effects of a leader's emotional displays. In a scenario study, participants with lower levels of agreeableness responded more favorably to an angry leader, whereas participants with higher levels of agreeableness responded more favorably to a neutral leader. In an experiment involving four-person teams, teams composed of participants with lower average levels of agreeableness performed better when their leader expressed anger, whereas teams composed of participants with higher average levels of agreeableness performed better when their leader expressed happiness. Team performance was mediated by experienced workload, which was highest among agreeable followers with an angry leader. Besides having important practical implications, the findings shed new light on the fundamental question of how emotional expressions regulate social behavior. © The Author(s) 2010.