Repetition of an assertion increases the degree of belief in that assertion. This reiteration effect is used to explain two puzzling findings in research on hindsight bias. First, the reiteration effect explains the asymmetry in hindsight bias for true and false assertions. This striking asymmetry has often been observed in experimental studies, but no rationale has yet been found. Second, the reiteration effect predicts a novel finding: Recalled confidence will increase in hindsight bias studies even if no feedback is given. The authors have checked both predictions against results reported in the literature; with some exceptions, the evidence supports them.