This chapter examines the components that constitute the Council system: the European Council and the Council of the EU (henceforth ‘the EU Council’ or simply ‘the Council’). Together, these institutions (the European Council and EU Council) form the part of the Union that unabashedly represents national interests in the European integration process. The EU Council is thus a site of intense negotiation, compromise-building, and at times acrimonious disagreement among the member states. Confusing to many academics and observers alike, the EU Council is not a single body, but rather a composite of national officials working at different levels of political seniority and policy specialization. From the heads of state and government, to the ministers, and all the way down the ladder to the expert-level fonctionnaires (officials), the EU Council and the European Council embed governments of the EU into a networked club of collective decision-making that deeply penetrates into the national capitals and domestic politics of the member states. In authority, scope, and procedural methods the Council system represents the most advanced, intensive forum of international cooperation between sovereign nation states in the modern world.