Institutional fragmentation has been less addressed by research when considering the specific context of transboundary river basins, settings that are often characterized by multiple regulatory frameworks as well as by a great range of uses and users of the river that intervene at different institutional levels. Considering that such contexts represent fertile ground for reinforced use rivalries and exacerbated power relations, it is key to fo­ cus on the very nature and results of such institutional fragmentation; in other words, it is necessary to explore the politics of institutional fragmentation in transboundary rivers. Three main bodies of literature are suggested as insightful perspectives to provide en­ hanced understanding of such contexts: (a) institutional fit literature: challenges of fits between institutions and ecosystems, (b) legal pluralism: interplay and co-existence of dif­ ferent normative orders, (c) polycentric governance: coordination modalities between dif­ ferent and independent decision-making centers.