Notification of co-riparian states of planned measures on shared watercourses has been widely accepted as an established principle of international water law, and is codified and elaborated in the United Nations Watercourses Convention. However, despite this wide acceptance, differences have arisen on operationalizing notification, including on which riparians are required to undertake notification, and which riparians are entitled to it. Issues have also arisen on how to deal with the different types of responses that may ensue following notification. The World Bank has been financing projects on international watercourses since its inception in 1946, and has built an extensive wealth of policies and experience in this field. This monograph discusses the historical and legal foundations of notification under international law, analyzes the policies and implementation experience of the World Bank thereon, and identifies comparators and synergies between the provisions of the Watercourses Convention and the Bank policies and practice.