States have different strategic cultures when it comes to legitimating the use of military force and its relation with other foreign policy instruments. However, increasingly, military operations are conducted in multilateral forums; EU military operations are one of the most notable examples of this development. While some claim that these operations reflect power relations between nations with different strategic cultures, others argue that these common missions involve states in a process of collective learning and convergence of interests. Drawing upon an advocacy coalition approach, this paper confronts the competing hypotheses in the case of European Union Force (EUFOR) Althea in Bosnia-Herzegovina (BiH), as the EU’s longest running military operation (since 2004). On the basis of policy documents and semi-structured interviews with policymakers and politicians, this paper concludes that the evolution of EUFOR Althea has been primarily the result of the power politics of different coalitions, but there have also been a few instances of learning.