The Common Agricultural Policy (CAP) was the European Economic Community's (EEC) first (and for a long time only) common policy. Following the trauma of World War II, it was based partly on the idea that the EEC should if possible be self-sufficient in food. Though building on pre-war national agricultural policies, the CAP was an essential part of post-war European welfare states; it extended the welfare state to farmers. In the early years of European integration, the CAP also had political objectives; in France its welfarist orientation was intended partly to guarantee rural political stability. These features were clearly visible in the concept of ‘agriculture’ that was elaborated in CAP law. Its basic idea was that public policy should support agricultural production and regulate access to agricultural markets. By the mid-1980s, however, the CAP was no longer central to the politics of European integration. Since then, due to both endogenous and exogenous factors, its policy objectives, fundamental rules, and organizational structures have largely been transformed. This article traces its evolution, discusses major reforms, and identifies future challenges. It emphasizes the impact of the international context, changes in regulatory goals and instruments within a stable Treaty framework, the interpretative role of the European Court of Justice, and the need for further reform.