This dissertation examines the processes of popular participation that shaped the 1988 Brazilian and1991 Colombian constitutions, focusing on the thousands of proposals submitted by ordinary citizens during each country’s constituent assembly. It argues that what made these constitution-making moments transformative was not the final legal text alone, but the unprecedented mobilization of people who had long been excluded from formal politics. These were not only symbolic gestures or top-down strategies for legitimacy, but also collective acts of political imagination. In both countries, constitution-making became a way to redefine the meaning of democracy and to claim new futures. By analyzing the content, circulation, and archival treatment of citizen proposals, the dissertation shiftsattention from the formal proceedings of the constituent assemblies to the political life unfolding outside of them. It shows how popular participation created a new horizon of expectation about who should participate in democracy, how rights might be defined, and how the state could be reimagined. Though many demands went unmet, the process left institutional traces—consolidating participatory mechanisms within both constitutions. These traces mark a historical shift— from resisting the state to attempting to remake it from within. Focusing on the Northeast of Brazil and the Southwest of Colombia, the dissertation foregrounds theregional and social diversity of participation and the uneven presence of the state across historically marginalized territories. It also examines the construction of the archives of participation themselves, highlighting the logistical and conceptual challenges of processing democratic input at scale. In doing so, it reveals how the promise of inclusion often clashed with the limits of bureaucratic legibility. Ultimately, it argues that these constitution-making processes marked a break with Cold War political culture— expanding political voice without redistributing power, and offering new democratic imaginaries at a moment of global transition.