Europe is the region of the world where the network of security institutions is the densest. Yet, these institutions did not erase differences about conceptions of force employment among European countries and between European countries and the United States. Why have concepts of military power and force employment remained distinct and varied in Europe, and yet, what facilitates their convergence at the European Union level into the ambiguous notion of crisis management? We argue that an important answer to these questions is endogenous to the military: both role conceptions and organizational frames of military institutions are key underlying aspects of the differences at the national level and of the common ground at the European Union level. We examine and compare empirically the role conceptions and organizational frames of the armed forces in France, Germany, Italy, and the United Kingdom since the early 1990s.