Moral convictions—attitudes that people report are connected to their beliefs about right and wrong—are known to have unique effects on behavior, from activism to intolerance. Less is known, though, about why moral conviction has these effects. I propose that the unique predictive force of moral conviction is partly attributable to the fact that attitudes that people construe as “moral” are social identities closely tied to the self-concept. First, consistent with the idea that moral convictions are tied to the self-concept, I find in two studies that intensity of moral conviction predicts (1) self-reported identity centrality and (2) reaction time to attitude-related stimuli in a me/not me task, even when controlling for reported attitude importance. Further, moral conviction also predicted participants’ scores on a dominant common factor that underlay both outcomes, suggesting that the association between moral conviction and the self-concept is not a mere artifact of method-related factors. Second, and consistent with the idea that moral convictions are social identities, I find evidence that participants used their moral convictions to perceive, categorize, and remember information about other individuals’ positions on political issues, and that they did so more strongly when their convictions were more identity-central. Finally, I find that the association between moral conviction and intolerance is partly accounted for by moral convictions’ centrality to individuals’ identities, suggesting that the conflict that results from moral disagreement may resemble that which accompanies other identities (e.g., race, gender) and therefore might be mitigated with existing prejudice-reduction strategies.