Jumping to negative conclusions about other people's traits is judged as morally bad by many people. Despite this, across six experiments (total N = 2,151), we find that multiple types of moral evaluationseven evaluations related to open-mindedness, tolerance, and compassionplay a causal role in these potentially pernicious trait assumptions. Our results also indicate that moralization affects negativebut not positivetrait assumptions, and that the effect of morality on negative assumptions cannot be explained merely by people's general (nonmoral) preferences or other factors that distinguish moral and nonmoral traits, such as controllability or desirability. Together, these results suggest that one of the more destructive human tendenciesmaking negative assumptions about otherscan be caused by the better angels of our nature.