This article examines the structure of the Treaty of Lisbon (the Treaty) which was adopted on December 13, 2007. In doing so, the article provides a short review of the emergence of this document and subsequently conducts a comparative analysis between the Treaty and the rejected European Constitution of 2004 highlighting both the differences and similarities between those two acts. The author argues that the differences between the Treaty and the European Constitution essentially of cosmetic nature. Although structurally the Treaty still resembles the previous Treaty of Nice of 2001, the contents of the Treaty of Lisbon incorporate the overwhelming majority of the provisions of the European Constitution. Simultaneously, the article points out the problems of the European integration arguing that further considerable enlargement of the EU would not promote the consolidation and deepening of the integration processes within the EU. Summing up the article, the author makes a conclusion that the Treaty of Lisbon, being an adapted version of the European Constitution, would certainly contribute to the transformation of the EU into a more effective structure. At the same time, the Treaty is just another stage in the history of the constitutionalization of the EU and on its (still very long) way to the political union.