This book addresses a key issue in higher learning, university education and scientific research: the widespread difficulty researchers, experts and students from all disciplines face when trying to contribute to change in complex social settings characterized by uncertainty and the unknown. More than ever, researchers need flexible means and grounded theory to combine people-based and evidence-based inquiry into challenging situations that keep evolving and do not lend themselves to straightforward technical explanations and solutions. In this book, the authors propose innovative strategies for engaged inquiry building on insights from many disciplines and lessons from the history of Participatory Action Research (PAR), including French psychosociology. The ongoing evolution of PAR has had a lasting legacy in fields ranging from community development to education, public engagement, natural resource management and problem solving in the workplace. All formulations have in common the idea that research must be done ‘with’ people and not ‘on’ or ‘for’ people. Inquiry of this kind makes sense of the world through efforts to transform it, as opposed to simply observing and studying human behaviour and people’s views about reality, in the hope that meaningful change will happen somewhere down the road. The book contributes many new tools and conceptual foundations to this longstanding tradition, grounded in real-life examples of collective fact-finding, analysis and decision-making from around the world. It provides a modular textbook on participatory action research and related methods, theory and practice, suitable for a wide range of undergraduate and postgraduate courses, as well as working professionals.