This study aims to analyze the transformation of regional institutions in Latin America within the framework of liquid regionalism and the phenomenon of institutional "melting." The research is qualitative, employing an inductive approach and a comparative case study strategy. The population consists of regional organizations in Latin America, with ALBA, UNASUR, and the Pacific Alliance selected as purposive cases. Data were collected through official documents, academic articles, and analytical reports. Validity and reliability were ensured via triangulation and comparative analysis. Data were analyzed using qualitative content analysis based on the typology of liquid regionalism—consultation, cooperation, and integration. Findings indicate that institutional melting is a structural crisis driven by weak institutionalization, ideological fragmentation, and lack of sustained regional leadership. ALBA and Unasur have suffered the most, while the Pacific Alliance, despite trade growth, has failed to achieve deep integration. It is concluded that liquid regionalism is a structural shift toward temporary, consultative arrangements, and resistance requires stronger institutionalization and long-term commitments