In recent decades, a growing number of international and regional organizations have sent personnel and resources, in various parts of the world, to prevent, halt conflicts, or to rebuild institutions afterwards. This multiplication of actors and interventions almost mechanically leads to intersecting, combining, and competing interests in sites of operations. This dissertation asks: How do external actors interact when they intervene simultaneously in the same sites? To study this phenomenon, I coin the term localized regime complex (LRC). LRCs are the geographically bounded extension of regime complexes that develop around a specific subject matter. They encompass the international, regional, and bilateral actors that intervene with staff and material resources in the same space, as well as the formal and informal agreements that link them together. Examining how interveners navigate this complex environment, attempt to achieve their goals, and invest material and immaterial resources is crucial in understanding how their strategies affect populations, which are deeply impacted but also tend to have little influence over international affairs. Empirically, this project looks at three iterations of the LRCs, which emerged from the interactions among external interveners in Bangui, the Central African Republic