This article presents some pacifist ideas developed in various economists' works since the origins of economic thought. The Classicals considered international peace to be a normal result (as well as a necessary condition) of economic development and human progress. Such a conception is also shared by other schools of thought, such as Utopian socialism or institutionalism. Some economists were active in the development of the pacifist movement before the First World War, which led to the organization of several international Peace Congresses. During the Cold War, certain economic studies on military expenditure and the arms race contributed to the denunciation of an excessive militarism. However, the post-Cold War disarmament highlighted the costs of the necessary peace investment. There is a substantial research agenda and a need for more academic economists to undertake analytical and empirical work in this important field.Pacifism, Liberalism, Veblen, Militarism, Peace movements,