This article suggests that the full significance of PMCs for international security is often missed because the concept of power framing these discussions is inadequate. The power to shape shared understandings of security is particularly neglected. The article argues that the emergence of PMCs has shifted the location of this power from the public/state to the private/market and, even more significantly, from the civil to the military sphere. The article reaches this conclusion in three steps. First, it suggests that PMCs have considerable power to shape the security agenda (Bacharach and Baratz). Second, it suggests that PMCs shape security understandings of key actors and hence their interests and preferences (Lukes's third dimension). These two facets highlight what I term the PMCs' epistemic power, located at the level of agency. Third, the article suggests that the action of PMCs have affected the field of security expertise, empowering a more military understanding of security which, in turn, empowers PMCs as particularly legitimate security experts. This third enlargement of the power concept highlights the ‘structural power' of PMCs related to their position in the field of security (Bourdieu).