How do voters react to news of political corruption? Information about corruption may mobilize citizens to demand political and institutional reform, but existing empirical evidence is mixed. We argue that the effects of information about corruption on citizen attitudes and voting behavior is moderated by political efficacy (perceived influence of activism on political outcomes), which varies considerably across and within emerging democracies. To test the argument, we draw on survey data from Afghanistan collected during the 2010 Kabul Bank crisis, which revealed corruption in the formal banking system. The unanticipated scandal unfolded midway through the collection of the survey, allowing us to adopt a novel quasi-experimental approach. The scandal led to an increase in perceived corruption in government and heterogeneous effects on voting via a political efficacy mechanism. Our argument and results clarify an important puzzle in the cross national literature on corruption and voter mobilization.