The article discusses the concepts of federation and empire in the context of the European Union (EU). Even if these two concepts are not usually contrasted to one another, the article shows that they refer to related type of polities. Furthermore, they can be used at a time because they shed light on different and complementary aspects of the European integration process. The article concludes that the EU is at the crossroads between federation and empire and may remain an ‘imperial federation’ for several decades. This could mean that the EU is on the verge of transforming itself to another type of project from the one which led to its creation.