Abstract
The parliamentary (political) groups of the EP are key actors in the legislative process in the EU. The EP is an unique supranational assembly because its members (MEPs) organise themselves as in national parliaments–based on ideological and political affinity. To understand how the EP work on a political level, we need to examine the parliamentary groups. It is essential to understand that those groups differ from the Europarties, the European political foundations and the European transnational federations.