This PhD project, conducted as part of the cross-organisational JCAR ATRACE project, investigates the role of knowledge and learning in fostering collaboration to manage flood and drought risks in transboundary river basins. The study examines how different types of knowledge, alongside processes of creation, dissemination, and shared learning, influence key collaborative mechanisms such as trust-building, priority alignment, and decision-making among diverse stakeholders. The research emphasizes the importance of understanding how knowledge and learning dynamics drive effective cooperation in complex, multi-stakeholder settings under conditions of uncertainty. By addressing these issues, the project seeks to provide actionable insights and strategies for enhancing transboundary water governance, ensuring more sustainable and resilient approaches to the management of shared water resources in a changing climate.