The political game in the European Union has changed. Nowadays, EU issues are politicized in the public mass arena and demand from the European leadership more than the traditional, thin top-down communication. Concerns about the European democratic deficit and the legitimacy of the EU have made it important to engage citizens in EU issues and actively win their support. Since citizens almost never have firsthand experience with EU issues, they are most likely to pick up political cues from media discourse. Several events have shown that many citizens have only recently discovered the implications of European integration. Apparently, much of the media discourse on EU issues emanating from unpoliticized consensual decision-making in interest-based arenas does not reach the citizens. By comparing the media discourse on the few EU issues in which citizens have become activated and engaged – either to challenge or to support European decision-making – with media discourse that has not engaged citizens, the mechanism can be unraveled that explains the conditions under which citizens most effectively become politically active regarding EU issues. It is expected that a discourse that is highly loaded with emotions is more likely to reach citizens’ hearts and minds, and thus lead to political action, than the usual technical and consensual manner of presenting European decision-making. Insights from collective action research and on media effect research are used to operationalize the key-concept “emotions”. Media discourse that generates sufficient arousal to attract the citizens’ attention and interest and that invokes the identity of an imagined community in relation to a sense of agency and injustice is most likely to mobilize European citizens, even on an EU issue.