This project aims at investigating the impact of the accession the European Communities to the Portuguese economy. Joining the EC in 1986 had a major impact in economic the relations between Portugal and its major trading partners, within Europe as well as with the rest of World. The relations between the Portuguese economy and the rest of Europe are of course secular and had major developments during the nineteenth century and also after 1950. During the nineteenth century the development of trade and capital flows with Western Europe increased rapidly. Such trends were halted during the interwar period, but they were resumed after World War II. In 1959, Portugal joined EFTA, which led to a sharp reduction of industrial trade barriers, which were further reduced in 1972 by the trade agreement signed between Portugal and EEC in that year. Thus in 1986 trade barriers between Portugal and the EC were already substantially reduced. Yet integration proceeded after adhesion and was enhanced in other areas, namely in terms of institutional arrangements and also in terms of financial flows.