This book analyses the role of legitimacy in explaining local actors' compliance with international peacebuilding operations. The book provides a comparative, micro-level study of local actors' reasons for compliance with or resistance to international peacebuilding. Specifically, it analyses three pathways to compliance -legitimacy, coercion, and reward-seeking - to explore local police officers' compliance with the reforms stipulated by the EU Police Mission in Bosnia and the EU Rule of Law Mission in Kosovo. The work constructs a holistic framework of the mechanisms connecting each pathway to compliance and measures legitimacy using micro-level indicators. This study not only shines light on the question why local actors comply, a crucial factor in mission effectiveness, but it also illuminates exactly how compliance works. The book contributes nuanced evidence about the often-heralded importance of legitimacy in peacebuilding, showing exactly in which situations local legitimacy matters and in which it does not. It is also highly relevant for policy-makers as it unpacks and explains the mechanisms behind local legitimacy, assisting in understanding this usually nebulous concept. This book demonstrates the need for micro-level analysis by revealing the relevant processes of legitimation usually hidden behind commonly perceived social fault lines, such as the Serb-Albanian divide in Kosovo. This book will be of much interest to students of peacebuilding, war and conflict studies, Balkans politics, security studies and International Relations.