The reform of the European Community's regional policies in the mid 1980s had its intellectual origins in theories of endogenous development and cumulative causation. These ideas shaped proposals put forward by the European Commission as early as the 1960s and provided the substance of the 1985 and 1988 reforms. The reforms were 'sold' politically, however, as part of the overall Single Market project, which was itself based on a very different economic model. The resulting contradiction goes far in explaining the perceived implementation failures of the regional policy reforms. In analysing this case, we seek to further and to refine the ongoing inquiry into the role of ideas and intellectual models in concrete policy-making.