This book examines the failure of more than 30 years of the Nagorno-Karabakh mediation and negotiations within the context of the broader Armenia-Azerbaijan violent conflict (1988-2023) and from the perspective of conflict resolution and peace negotiations. The book focuses on peace proposals advanced by the OSCE Minsk Group, and after 2022, parallel, often competing mediation by the United States, European Union, and Russia. The book examines the conflicting parties? (Nagorno-Karabakh Republic, Armenia, Azerbaijan) response to peace proposals, their motivations, third-party intervenors? role, missed opportunities, geopolitical considerations, principal reasons the process eventually failed, and lessons learned for peacemaking in general. Research for the book includes primary source material from the OSCE and UN archives, open-source materials from the belligerent parties, the U.S., European states and institutions, Russia, scholarly books and essays on the subject, and interviews with decision makers, diplomats, mediators, and commentators.