Using NATO-CSDP relations in the field of crisis management as a case study, this article explains the implications of institutional overlap on multilateral security policy. Bringing together realist and institutional insights in order to understand to what result overlapping institutions interact, it shows that it is necessary to study institutional positions in conjunction with state preferences. Institutional overlap has deep consequences for organizational performance. In instances of heterogeneous preferences and heterogeneous institutional positions, I argue that formal institutional paths can be foreclosed to inter-institutional security cooperation of planning and conducting crisis management operations. As a result we observe sub-optimal and inefficient institutional outcomes in form of blocked cooperation, long delays in sending troops, wasted resources as well as the absence of security agreements and (political and military) strategic dialogue. Civilians’ and soldiers’ lives are put at risk in conflict areas.
