Abstract
The European Union is an example of deep and complex regional economic integration. The strong gravity of the EU resulted in its gradual enlargement. Poland joined the European Union in 2004 after a long and difficult accession process combined with transition of the Polish economy. The accession to the EU created significant advantages and true challenges for the Polish economy and the Polish society. The paper presents accession procedure to the EU from the Polish perspective and gives evaluation of strengths and weaknesses of the Polish economy. It also discusses economic, social and political effects of integration with the European Union structures from the perspective of the first decade of membership in the EU structures.