Japanese foreign policy in international political affairs, particularly after the Second World War, was criticized as relying solely on bilateralism and dismissed as blindly emulating American foreign policy. This book examines Japanese multilateralism from the Paris Peace Conference in 1919 to its latest bid for a permanent seat on the UN Security Council. At the threshold of the twenty-first century, the author asserts that Japan can play a more proactive role in the United Nations and in the Asia-Pacific through its cooperative security approach with emphasis on prevention of conflicts.