If participation has been an ideal in politics since ancient democracy, in art it became central only with the avant-gardes emerging from WWI and the Russian Revolution. Politics and aesthetics are still catching up with each other. In the 21st century, since the revolutionary unrest of the 1960s, participation in art and architecture has lost its utopian glow and become the focus of a fierce debate: does 'participatory' art and architecture shape social reality, or is it shaped by it? Contemporary critics see in participation only technocratic control, while others embrace it as a viable politics in an era of global capitalism. This innovative book breaks the impasse by looking at how participants themselves exert power, rather than being victimized or liberated from it. From artists hijacking Google Earth to protesters setting up a museum of the revolution in Cairo, art, architecture and daily life are explored in their participatory dimension.