Book excerpt: Sustainable peace involves more than simply including youth in official peacebuilding mechanisms or recognizing their local peacebuilding work; it requires a transformation in thinking about the youth as actors in the world of security and peace. Using case studies from around the globe, the contributors to this volume analyse why states are afraid of their young people, why 'youth participation' in formal peace processes matters but is insufficient, and ways that young people are working outside of official systems to create and nurture peace on their own terms. The volume offers guidance for ways to bridge the disconnect that exists between institutional assumptions and expectations for youth as peacebuilders and the actual sustainable peace leadership of youth. Throughout, it emphasises a critical approach to peacebuilding with, for and by youth.