The emergence of postwar welfare states in Europe is usually understood as a social and political phenomenon, as a social policy to prevent against forms of mass poverty and to grant general social rights and entitlements to populations during a period of rising prosperity. Beyond these sociopolitical aspects, the foundation of systems of social security after 1945 also had important cultural and epistemic implications. The promise of the state to provide a generalized form of security represented an important cultural factor in securing the social and political stability of postwar societies in Europe. This article examines some exemplary aspects of the meaning of social security by tracing their historical roots and their effects on postwar welfare states in Western Europe. In order to chart the various, interconnected cultural meanings of social security, it juxtaposes two institutional contexts in which social security and prevention were discussed: an international organization of social security experts and a Swiss life insurance company with an innovative health promotion service. The article shows how security was seen ultimately as an utopian response to the multiplication of risks and damages through the processes of industrialization and modernization and thus reveals how security served as both a technical concept for managing integrated systems of insurance and an instrument of control and calculation to help administer the economic and social policies of modern societies. By focusing on the example of life insurance, it demonstrates how security acted as an umbrella term for a generalized model of prevention that targeted the specific risks of a modern, middle-class consumer society.