Three studies tested the hypotheses that extraverts demonstrate better mood maintenance abilities than introverts and that these mood regulation abilities can account for the higher habitual happiness of extraverts. Using self- and peer-rated trait measures, Study 1 provided multimethod evidence that mood maintenance, but not mood repair, accounted for the link between extraversion and pleasant-unpleasant trait mood. Study 2 replicated this finding in a different sample of self-reports. Using a within-subjects design, Study 3 demonstrated that when confronted with an affectively ambivalent situation, extraverts maintained a more positive affect balance than introverts. Habitual mood maintenance mediated the effect of extraversion on pleasant-unpleasant affect change. Taken together, the findings support a self-regulation explanation of the extraversion-pleasant affect link.