The principle of integration is the backbone of sustainable development, yet its practical application remains elusive. How can States integrate the economic, social and environmental dimensions in the governance of common goods? This book seeks to address this question by examining a particularly sensitive domain of cooperation: the international watercourses. From the Mekong to the Senegal River and from the Great Lakes to the Danube, it analyses the legal and institutional instruments of nine international watercourse cooperation regimes to determine how the principle of integration is put into practice. This book finds that there are several instruments underutilised or entirely unused, offering potential opportunities for improvement.