Why do European Union (EU) member states sometimes respond collectively to violent humanitarian crises and civil wars while, at other moments, they use different institutional channels to restore peace and stability? More than once, EU states have pondered, hesitated, disagreed and let others interfere when civil war, war crimes and human suffering were looming. Instead of using the EU’s military crisis management capacities, member states have acted through different institutional channels such as the North Atlantic Treaty Organization (NATO), ad-hoc coalitions of states or single state-led operations to contribute to the resolution of violent crises. At times, they have decided not to intervene at all. Why does Europeans’ involvement in military crisis management vary so strikingly? This PhD project develops a three-stage model to examine European states’ readiness to intervene. I apply this model to the conflict in Libya during 2011, the post-electoral crisis in the Ivory Coast during 2010/2011, the civil war in the Central African Republic during 2013 and 2014 and the fight against Boko Haram in Nigeria and the Lake Chad region. The findings show that much of the variation in Europe’s responses to international crises can be explained through domestic preferences, their international feasibility and the ability and willingness of European states to find a common agreement.