How does one measure ‘success’ in UN peacekeeping missions? What is meant by a mission which is only partially successful, or in some part a failure? To answer these questions, it is essential to look at two dimensions of success: the establishment of order and the accomplishment of mandate. Using the cases of UN peace operations in Somalia, Sierra Leone and Liberia, this study rejects the classification of these missions as the ‘worst’ context for ‘transitional politics’, and instead demonstrates that peace operations may succeed, partially or totally, in challenging contexts, Diverse outcomes of UNPKO are better explained by the type of intervener and the strategy employed than by the type of context. This research demonstrates that for a peace operation in a civil conflict, the adoption of a deterrence strategy works best for re-establishing order, while the involvement of a great power often improves the chances of a peacekeeping mandate being fulfilled.