An explanation of the recent wave of constitutional changes in favor of more permissive reelection rules in Latin America is presented based on a principal-agent model of intraparty relations within the presidential party. The theoretical model suggests causal mechanisms through which institutionalized presidential parties constrain the decision to scrap term limits. The theoretical implications are tested using both quantitative and qualitative evidence. Results from logistic regression suggest that the likelihood of removing term limits in Latin American countries (1990-2013) significantly declines with the level of presidential party institutionalization. Case study evidence illustrates the operation of the theoretically-derived causal mechanisms.