We, as humans, are currently facing urgent socio-ecological challenges (climate change, demographic increase, booming inequalities, etc.). These challenges are reinforced by systems of financial control at the international level, extractive natural resources strategies, lack of effective democracies, the surge in conflicts and wars, etc. This book is based on the assumption that these challenges cannot be faced without the enhanced participation of all stakeholders – from citizens to policymakers – in the decisions that affect our social-ecological systems. This means that stakeholders must no longer simply be informed, but acquire the capacities to decide, act and adapt autonomously. In this sense, participation must be transformative. This book argues that this transformation needs to be accompanied by approaches, methods and concrete feedbacks. Therefore, this book aims to give an account of a diversity of practices and methods used to involve the various stakeholders, including the public, in transformative decision-making towards Socio-Ecological Sustainability. It answers questions such as: How to engineer a participatory process? How can facilitators acquire the skills needed to facilitate such a process? How can role-playing games support decision and change? How to design territorial development plans with thousands of citizens? What digital platform can be designed to support participatory policy making? How can the impact of a participatory process be monitored and evaluated? What is the role of experts in these processes?