Public engagement experiments are currently proliferating. State-commissioned experiments have included citizens’ juries, citizens’ councils, deliberative polls and consensus conferences; media experiments have used ‘voting’ and plebiscites in many different kinds of television programmes or entailed the creation of online political ‘games’; social movement practitioners have experimented with the orchestration of translocal political events and used internet technologies to help cultivate temporary alliances for bursts of political activism. These and many other apparently novel approaches to public engagement are already being investigated by researchers concerned with either state, media or social movement politics (see, for example, Barnes et al, 2007 and Goodin, 2008 for an exploration of state experiments; for media experiments, see, for example, Livingstone, 2005 and Riegert, 2007; for social movement experiments, see, for example, Holloway, 2002 and de Sousa Santos, 2007). While rigorous and extensive, this scholarship has not so far compared different kinds of experimentation and therefore explored relationships of similarity and difference between these forms of emerging practice. This gap in the literature is significant: state, media and social movement practices have not so far been viewed as part of a single extended field of practice and the emergent properties of this field have not so far been investigated. As experiments increasingly compete with each other for people's attention, the task of comparing how different experiments across different domains are designed, mediated and participated in becomes more important. And as boundaries between state, media and social movement practices and the publics that they appeal to become less easy to discern, so it becomes more important to study these dynamics and their effects.

Practices that work to engage and involve publics as participants in politics are not in themselves novel. However, with the legitimacy and authority of voting, elections and institutional politics on the wane (Mair, 2006; Stoker, 2006; Hay, 2007), it is becoming increasingly important to research new sites and ways of mobilising people as political actors – especially if contemporary transformations in politics and forms of public action are to be understood and engaged with.

The PhD (Mahony, 2008) on which this chapter draws was designed to begin to address this issue by investigating public participation experiments instigated by state, media and social movement actors in order to explore and compare how publics are brought into being by different kinds of participative events.