While there exists a plethora of theories aiming to make sense of the European Union and its foreign policy, no single existing theory has yet managed to capture the multi-actorness of what can be referred to as “the broader area of EU and European foreign and security policy”. A conceptual framework building on the current literature of differentiated integration, which has become a permanent feature of European integration, may fill that gap. Based on a holistic approach to EU foreign and security policy, looking at both formal and informal processes, such a framework explains the multi-actor character of the EU, while introducing five roles – leaders, followers, laggards, disruptors or leavers – that actors can play in the integration process, either to bring it forward or halt it.