European countries have been working for fifty years to establish a single market. In at least one respect they have succeeded spectacularly: the number of participating countries has grown enormously since 1957. This 5th European Outlook examines the question whether the internal market has also succeeded in another respect, that is, in improving free trade, free investments and free migration between the participating countries. Looking back, the common market has clearly contributed to prosperity in Europe over the past fifty years. Looking ahead, there is scope for further market integration in Europe.