Peace is an elusive concept, especially within the field of international law, varying according to historical era and between contextual applications within different cultures, institutions, societies, and academic traditions. This Research Handbook responds to the gap created by the neglect of peace in international law scholarship. Explaining the normative evolution of peace from the principles of peaceful co-existence to the UN declaration on the right to peace, this Research Handbook calls for the fortification of international institutions to facilitate the pursuit of sustainable peace as a public good.