This chapter outlines the significance and urgency of the current global water crisis and demonstrates that the existing international legal architecture for transboundary freshwater ecosystems requires significant improvement to meet current and predicted transboundary water challenges, resolve conflict and strengthen cooperation. The chapter sets out the three overarching objectives of the book. First, to understand the rising impact of regional approaches to international law on transboundary freshwater ecosystems. This includes identifying the contribution of the UNECE Water Convention and other relevant UNECE environmental instruments as a coherent legal regime. Second, to provide a more coherent understanding of the relationship between the UNECE environmental regime, international water law, international environmental law and general international law. This includes examining the contribution of the UNECE regime to cornerstone rules and principles of international water law and emerging or missing concepts such an ecosystem approach or public participation. Third, to understand how the UNECE regime adds to or interacts (on a normative and an institutional level) with river basin agreements, river basin commissions, European Union water law and national law. The introduction highlights the timely nature of the enquiry against the contemporary context and frames the book’s place against existing writing on this subject.