The theory and practice of civil disobedience has once again taken on import, given recent events. Considering widespread dissatisfaction with normal political mechanisms, even in well-established liberal democracies, civil disobedience remains hugely important, as a growing number of individuals and groups pursue political action. 'Digital disobedients', Black Lives Matter protestors, Extinction Rebellion climate change activists, Hong Kong activists resisting the PRC's authoritarian clampdown...all have practiced civil disobedience. In this Companion, an interdisciplinary group of scholars reconsiders civil disobedience from many perspectives. Whether or not civil disobedience works, and what is at stake when protestors describe their acts as civil disobedience, is systematically examined, as are the legacies and impact of Henry Thoreau, Mahatma Gandhi, and Martin Luther King.