People routinely engage in dishonest acts without feeling guilty about their behavior. When and why does this occur? Across three studies, people justified their dishonest deeds through moral disengagement and exhibited motivated forgetting of information that might otherwise limit their dishonesty. Using hypothetical scenarios (Study 1) and real tasks involving the opportunity to cheat (Studies 2 and 3), we find that dishonest behavior increased moral disengagement and motivated forgetting of moral rules. Such changes did not occur in the case of honest behavior or consideration of the behavior of others. In addition, increasing moral saliency by having participants read or sign an honor code significantly reduced or eliminated unethical behavior. While dishonest behavior motivated moral leniency and led to strategic forgetting of moral rules, honest behavior motivated moral stringency and diligent recollection of moral rules.