The European Union (EU) has always expanded since the initial stages of the European Coal and Steel Community (ECSC) in 1951 and the European Economic Community (EEC) in 1958 the six internal countries (Belgium, France, Germany, Italy, Luxembourg and the Netherlands). Since its origins, the EU has integrated a considerable number of member states, reaching twenty-eight, and some other countries are currently in the process of joining and are eagerly waiting to join the already large family of the European Union. Over the years from the origins of the EU to its current state, many theories on European integration have been developed, with the idea and aim of explicating and realizing the direction of the "character" of the EU, through the process of European integration, also theorising the esteem of the state -relationships of future candidate member states and impact on governments that are under unilateral joint governance: the EU. Theories regarding European/regional integration have often been criticized and/or rejected due to the EU's earlier origins characteristic of neofunctionalism (Haas 1958; Lindberg 1963) which suited it at the time, but were subsequently rejected in favor of intergovernmental theory (Hoffmann 1964; 1966) as various events unfolded. Time passes and many events ensue, which require the change or rejection of theories first considered valid and then overcome; this is why theories about the “character” of European integration are still under scrutiny by scholars, as there is no finite theory to explain the precise character of the EU. The process of European integration was achieved after the signing of the Treaty of Paris by the Six Internal Countries in 1951, who argued that their economies... at the center of the paper... support of mentalists and neofunctionalists). Therefore, in conclusion Liesbet Hooghe and Gary Marks point out that theorizing about European integration should no longer focus on economic interests as intergovernmentalists and neofunctionalists so profoundly argue. In conclusion, the puzzling topic of European integration theories, as we have mentioned, will remain an open question. -concluded debate among scholars and theorists, as there is no finite explanation to the ever-changing and evolving conditions of the European Union and its integration process, mainly due to the numerous events that constantly shape the integration process. Works Cited George, Stephen and Ian Bache. "Theories of European integration". Politics in the European Union. 3rd ed. Oxford: Oxford UP, 2010. 3-17. Print.Theories of European integrationPolitics in the European UnionIan Bache