This paper explores the economic consequences of the enlargement of the European Union with countries from Central and Eastern Europe. We focus on integration aspects that go beyond the reduction of formal trade barriers, namely accession to the internal market and free movement of labour. The economic implications for sixteen industries in several European countries are assessed by using WorldScan, a CGE model for the world economy. The results suggest that the candidate member states will gain substantially from accession to the internal market, although some sectors in these countries will shrink. Most EU countries will experience small welfare increases. We also find that the internal market effects are large compared to the economic effects of removing formal trade barriers and migration.