When and why do legislatures impeach presidents? We analyse six cases of attempted impeachment in Paraguay, Brazil and Peru to argue that intra-coalitional politics is central to impeachment outcomes. Presidents in Latin America often govern with multiparty, ideologically heterogeneous coalitions sustained by tenuous pacts. Coalitions are tested when crises, scandals or mass protests emerge, but presidents can withstand these threats if they tend to allies’ interests and maintain coalitions intact. Conversely, in the absence of major threats, presidents can be impeached if they fail to serve partners’ interests, inducing allies to support impeachment as acts of opportunism or self-preservation.