In 2006, Barack Obama wrote that the 'framework of our constitution' is designed 'to force us into a "deliberative democracy" in which all citizens are required to engage in a process of testing their ideas against an external reality, persuading others of their point of view'. His statement is just one of the many examples of the contemporary relevance of deliberative democracy. But where does this model come from? When was it born and how did it develop? Starting from the 1980s, this book provides the first, complete history of the idea of deliberative democracy, analysing its relationship with the earlier idea, and practices, of participatory democracy in the 1960s and 1970s. The author provides a lucid and detailed analysis of the texts and authors that have contributed to this theoretical field and, in the final chapter, proposes a possible guiding map of today's complex deliberative field, in its present configuration.