From modern slavery to environmental breakdown, the most urgent challenges of our time demand approaches that can work with complexity, rapidly adapt, and catalyse lasting change through the agency of ordinary people.This book introduces Systemic Action Research (SAR) – a participatory methodology designed to transform “hard to shift” patterns and dynamics in systems. Having implemented more than 30 large-scale SAR programmes worldwide, the authors combine systems thinking, complexity theory, and participatory practice to show how to design, facilitate, and evaluate change processes involving large numbers of system actors in interlinked action research initiatives. Featuring rich case studies, this is an invaluable guide for those committed to enabling large-scale social transformation and tackling complex crises.