The existing assessments of EU politicization have predominantly focused on the media and in the actors that are reported in that arena. This chapter offers a novel approach to the study of EU politicization by focusing, instead, on the institutional arena of six EU countries. Using the MAPLE dataset of parliamentary debates, with a total of 724,963 speeches covering a period of 20 years, this chapter offers a comparative and longitudinal analysis of EU politicization at the institutional level, assessing the impact that the Eurozone crisis had in the parliamentary debates of the EU. Automated and manual content analysis methods are used to answer three main questions: Has the EU been politicized at the institutional level? Did the Eurozone crisis affect the politicization of the EU in parliaments? What characteristics of political parties have determined the salience and contestation of the EU topic? Our results suggest that the EU has not been, in the past 20 years, a very salient nor contested topic at the institutional level. However, we find that the parties’ contribution to the democratic legitimacy of the European integration varies significantly, with the parties’ position on the EU topic being the strongest determinant of EU politicization.