This study argues that economic vulnerability causes citizens to participate in clientelism, a phenomenon with various pernicious consequences. To examine how reduced vulnerability affects citizens’participation in clientelism, we employ two exogenous shocks to vulnerability. First, we designed a randomized control trial to reduce household vulnerability: our development intervention constructed residential water cisterns in drought-prone areas of Brazil. Second, we exploit rainfall shocks. We find that reducing vulnerability significantly decreases requests for private goods from politicians, especially among citizens likely to be in clientelist relationships. Moreover, reducing vulnerability decreases votes for incumbent mayors, who typically have more resources for clientelism.