Book excerpt: Using empirical qualitative research, this book conceptualises and demonstrates the value of local practical knowledge for peacebuilding in the context of Northern Ireland. There are increasing calls to involve local people to ensure legitimacy, relevance, and sustainability when seeking to build peace and transform violent conflict. However, as peacebuilding becomes increasingly professionalised, this raises fundamental questions about whose knowledge matters for building peace and what kind of knowledge matters. Seeking to address these questions and to learn from applied practice, this book provides a qualitative empirical research study, investigating 40 practitioners active in conflict transformation at a grassroots level in Northern Ireland over 50 years. This research led not only to recapturing lost knowledge from practitioners, but also to a neglected ‘virtue’ – the Aristotelian concept of practical wisdom, phronesis. This book argues that phronesis has deepened our understanding of why ‘local’ practical knowledge is vitally important and calls for its global rediscovery as knowledge necessary for building sustainable peace. This book will be of much interest to practioners and students in the fields of peacebuilding, conflict resolution, philosophy, and British and Irish politics.