What explains the sustained political engagement of social activists, and how does it differ from political party members? This article addresses these questions by examining the Chilean Constitutional Convention (2021–2022), a failed experience of a constitution-making body elected after the 2019 social protests. Using a quasi-experimental design based on a difference-in-differences analysis of an original dataset of former delegates and near-winners, this study finds that former delegates are more likely to remain politically active than the control group. However, outcomes vary across the delegates' profiles: party members often escalate within political hierarchies or become advisors, while social activists face barriers to sustained engagement. This research advances the literature on the biographical outcomes of social movements by bridging the discussions on elites' political trajectories and social mobilization consequences at the individual level.