Economic power, income and employment diverge extensively within the European Union (EU) – both within and between Member States. The reduction of this gradient is the declared political goal at the European and national levels. Although regional economic research has embraced this topic, hardly any reliable findings are available as to the extent of the effect that the eastwards expansion and the economic integration of the EU have had on the development of regional disparities. Moreover, to what extent and why the development of employment at various different levels of qualification is different from region to region is still largely unexplained. Based on a wide collection of data and econometric analyses, Friso Schlitte's book makes an important contribution to closing these gaps in research.