IN 1990, Gøsta Esping-Andersen published The Three Worlds of Welfare Capitalism, a work which has turned out to be the single most important and decisive contribution to welfare state research in the past thirty to forty years. In essence, Esping-Andersen argued that we can observe systematic variation in the character of the developed welfare states of the West, which he grouped into three distinct welfare state models: a Scandinavian social democratic model, a conservative continental European model, and a liberal Anglo-Saxon model. This chapter provides a short description of Esping-Andersen’s three regimes; introduces a fourth, Southern European model, which will then be described in somewhat more detail; and outlines a historical and genealogical account of the development of all four models. Finally, the chapter briefly expands on the comparative perspective with a short discussion on whether the regime concept or the understanding of distinct welfare models can also be applied to other regions, such as Latin America and Asia.