This book explores the role of cities in the EU in facilitating civic participation through the commons (CPC), through the prism of constitutional principles.It fills a gap by providing a much-needed theoretical framework for commons-oriented initiatives. It focuses on democracy, participation, local governments and cities, by looking at the two legal orders of the European Union and the Council of Europe. At its core is the case study of Italy, where there is institutionalised collaboration between society and the State in over 320 cities. It shows that by leveraging the four key European constitutional principles of participation, local self-government, subsidiarity and solidarity, all EU cities can act as drivers of the commons. A fascinating and innovative exploration of civic participation through the commons that reinforces local democracy.