Seven studies demonstrate that threats to moral identity can increase how definitively people think they have previously proven their morality. When White participants were made to worry that their future behavior could seem racist, they overestimated how much a prior decision of theirs would convince an observer of their non-prejudiced character (Studies 1a-3). Ironically, such overestimation made participants appear more prejudiced to observers (Study 4). Studies 5 to 6 demonstrated a similar effect of threat in the domain of charitable giving—an effect driven by individuals for whom maintaining a moral identity is particularly important. Threatened participants only enhanced their beliefs that they had proven their morality when there was at least some supporting evidence, but these beliefs were insensitive to whether the evidence was weak or strong (Study 2). Discussion considers the role of motivated reasoning, and implications for ethical decision making and moral licensing.