This article explores major theoretical approaches to the study of European integration, European Union (EU) as a global power, and the EU Common Foreign and Security Policy. The argument presented here is that only a combination of both International Relations and European integration approaches will allow us to understand the very premises of the European integration project in terms of both internal and external – international-aspects. This approach will be complementary to the attempts by researchers those who call to mainstream European studies and an appeal in favor of abounding the project of conceptualizing the EU as a single case or as being Sui generis. This article argues that, despite serious attempts by scholars of the field of European studies, it seems difficult to theorize European integration. The established literature to the existing political entities seems less relevant to study EU due to the union’s unique identity. Theories of EU integration are unable to explain or predict the process of integration, but they are normally outpaced by events.