We study dynamic models of electoral accountability. Politicians' policy preferences are their private information, so officeholders act to influence the electorate's beliefs — i.e., to build reputation — and improve their re-election prospects. The resulting behavior may be socially desirable (good reputation effects) or undesirable (bad reputation effects). When newly-elected officeholders face stronger reputation pressures than their established counterparts, good reputation effects give rise to incumbency disadvantage, while bad reputation effects induce incumbency advantage, all else equal. We relate these results to empirical patterns on incumbency effects across democracies.