How do institutional arrangements established by law become operational in practice? It takes work for them to develop problem-solving capabilities and win recognition from others-what the authors call practical authority. Drawing from a decade-long, multi-site study of efforts to transform freshwater management in Brazil, the authors show how an assortment of protagonists-from state officials to university professors to activists-struggled to breathe life into new institutional designs. Their account weaves together three decades of national and state law-making with experimentation in establishing new kinds of participatory water management organizations. Exploring this process in sixteen river basins, the authors examine why some of those organizations adapted creatively to challenges while others never got off the ground. To approach this complex, volatile, and non-linear process of transformation, the book develops a framework for investigating the actions and practices of institution-building.