For a long time now, social policy has intervened not only in emergency situations and precarious fringe areas of society, but instead influences in varied ways the living conditions of the entire population. This completed postdoctoral project looks at two distinctive phases of the development of the West German welfare state: the period of expansion in the 1960s and early 1970s, during which social policy transformed against the backdrop of optimistic thinking about what might be possible in the future into an active ‘societal policy’, and the years ‘after the boom’ from the second half of the 1970s – a phase in which growing unemployment, an aging population and altered gender roles profoundly changed the scope and priorities of social policy actions and brought about the transition to a politics of cost reduction and consolidation that persists to this day. The study correlates the rise, zenith and limits of the expansion of the welfare state. It enquires after the methods and possibilities of the reform of central institutions under the conditions of prosperity and austerity, as well as after the long-term effects of such reform processes, and investigates moreover knowledge systems, actor constellations and the social consequences of decisions in social policy. In this way, it makes a contribution to historicising West Germany and helps to explain the genesis of new problem areas that shape the face of our present.