This series of five lectures (1) examines the nature of international environmental disputes and their significance for international order; ( 2) surveys and analyzes relevant experience in the settlement of international environmental disputes, with particular attention to environmental problems relating to international rivers and lakes, the oceans and the atmosphere; and (3) suggests some of the principles, approaches and techniques through which international law and institutions may be able most effectively to contribute to the avoidance and adjustment of international environmental disputes and the protection of the international community's interest in the environment. The five lectures deal, respectively, with: (1) preliminary questions, including the characteristics of international environmental disputes, obligations concerning the avoidance and settlement of disputes, and methods of dispute avoidance and settlement; (2) disputes concerning international rivers and lakes; (3) disputes concerning the marine environment; (4) disputes concerning air pollution and in other environmental contexts, such as outer space, Antarctica, nuclear testing, weather and climate issues, international trade and investment, and other problem areas; and (5) a conclusion which proposes a number of principles of environmental dispute settlement, discusses the usefulness of various institutional means, emphasizes the importance of protecting the international community's interests, and suggests prospects for the future. The proposed principles on environmental dispute settlement, explicated and discussed in the conclusion, are: (1) the principle of environmental responsibility; (2) the principle of diverse approaches; (3) the principle of factual knowledge; (4) the principle of dispute avoidance; (5) the principle of predictability; (6) the principle of flexibility; (7) the principle of lowest-level solutions; (8) the principle of non-legalistic solutions; and 9) the principle of co-ordination. The five lectures were presented as an integrated course at the summer 1975 session of the Hague Academy of International Law in the Hague, the Netherlands and published in the Academy's Recueil de Cours, Vol. I '1975.