The book provides a comprehensive analysis of one of Europe&s most enduring unresolved conflicts. Despite twenty-five years of intensive international military intervention, territorial administration, and mediated negotiations, a sustainable and comprehensive peace agreement between Kosovo and Serbia remains elusive. This book addresses the fundamental question: Why has the conflict remained in a deadlock despite continuous international engagement? The book moves beyond descriptive history by applying a combined approach of Ripeness Theory, Readiness Theory, and Spoiler Theory. This framework allows for a nuanced exploration of the strategic and psychological dimensions that influence negotiations in an entrenched conflict. From the 1999 Rambouillet Accords, through Resolution 1244 to the 2007 Comprehensive Proposal for a Kosovo Status Settlement, the 2013 Brussels Agreement, the 2020 Washington Agreement, and the 2023 Ohrid Agreement, every major diplomatic milestone is analysed. A dedicated anafysis focuses on the internal peace process, examining the integration of the Kosovo Serb community through shifting eras. It also offers a critical case study on the limitations of "creative ambiguity" and the shortcomings od technical and transactional diplomacy in resolving ethno-political disputes. The book critically examines the roles of various international actors, including the EU, US, Russia, and NATO, assessing how their internal divisions or shifting priorities have influenced the conflict. The book is essential reading for scholars and students of International Relations, Conflict Resolution, and Balkan Studies, as well as diplomats, policy-makers, and practitioners involved in international mediation.