The ongoing European integration represents an ambitious process without historical precedent and, largely, a story of overwhelming success. Yet, even after several rounds of deepening and widening the European Union, there is still much uncertainty and even doubt at any further integration step. In particular, concerns refer to a change of the international and interregional division of labour, by which some less-developed regions might run a risk of brain draining and some developed regions might be affected by “out-migration” of jobs to low-income regions. Research in this field is therefore of high social relevance – and, besides, it is also attractive to the researcher, given the natural-experiment nature of the European integration process. This book brings together the research results of a research project “The impact of European integration and enlargement on regional structural change and cohesion” (EURECO), which was undertaken with financial support from the European Community’s 5th Framework Programme.