This chapter examines the emergence, expansion, variation, and transformation of the welfare state. It first considers the meaning of the welfare state, before discussing three perspectives that explain the emergence of the welfare state: the functionalist approach, the class mobilization approach, and a literature emphasizing the impact of state institutions and the relative autonomy of bureaucratic elites. It then describes the expansion of the welfare state, taking into account the impact of social democracy, neocorporatism and the international economy, risk redistribution, Christian democracy and Catholic social doctrine, and secular trends. It also explores variations among developed welfare states, as well as the effects of the welfare state, and concludes with an analysis of the challenges and dynamics of contemporary welfare states. The chapter shows that the welfare state is a democratic state that guarantees social protection as a right attached to citizenship.