During the last two decades, comparative social-policy research has improved our understanding of the causes, processes, dynamics, and consequences of change in social policies. It has also broadened the horizon of sociological theory and research. It has shown that understanding the nature and generosity of welfare-state policies is crucial for explaining the cross-national differences in social structures as well as the effects of social-policy reforms on social inequality, poverty risks, social cleavages, and social cohesion. This review of the development of social-policy research focuses on theory and research in the field,with its primary emphasis being on sociological social-policy research in German-speaking countries.