A higher level of unity and cohesion across the European Union member states is an important aspect of European integration though it has a rather ambiguous nature. The Law on the Common Market, which aims to increase the economic efficiency of the EU, became a subject of extensive discussions among researchers suggesting that its viability at the political and socio-economic levels depends on a fair distribution of gains among the countries and regions of the Community. These discussions resulted in a considerable increase in funding allocated for the development of the EU regions from the EU Structural Funds and the Cohesion Fund aiming to reduce regional disparities. The present analysis and the assessment of convergence processes (GDP p...