A new art of taking action is intended to activate urban societies and ensure participation—and is therefore a matter of political responsibility. This book examines the conditions and possibilities of these artistically initiated projects within urban space that are aimed at participation in shaping the city, thereby bringing together political activism, social work, and urban planning. It takes a look at the consequences of this mostly explorative and experimental urban practice for the creation of new fields of work for a variety of involved parties and their self-understanding. Supposed utopias are envisaged communally in these works and tested in realistic conditions. Art becomes a collective process, a shared urban practice. The focus is therefore no longer on merely dealing with and illustrating topics, but on widespread action targeted towards change. It is therefore about action instead of negotiation, about art as communal urban design.