Democracies are struggling to respond to the climate crisis. One promising approach to the ecological transition is based on innovations involving panels of citizens drawn at random. Many countries have experimented with this form of deliberative democracy at national and local levels. These citizens’ assemblies formulate public policy proposals. The French Citizens Convention for Climate is the largest in terms of size, duration and mandate. Thanks to a multi-disciplinary field survey involving around twenty researchers, this book provides an understanding of the complexity of this experience from several angles: procedures and processes; the identity and roles of its members; relationships with expertise and representatives; evaluation and comparison with other cases. Deliberative Democracy and Ecological Transition plays an important role in reflecting on an original practice of democratic innovation and its potential for fair governance of climate policies.