Reactor is a group of contemporary artists whose collective practice is focused on creating projects in which audiences become active participants. By developing situations that leave no room for the passive observer Reactor create work in which, rather than being forced, active engagement becomes the norm. Group dynamics and social interaction come to the fore, as participants immerse themselves in an unknown that invites risk-taking and a heightened sense of reality. The multilayered and social nature of the experience encourages diverse interpretations of the meaning of the work and emphasises the responsibility individuals have in forming collective perceptions of reality. A strong interest in community building and the social microcosm pervades the work, and social technologies – from Web based networking to complex CCTV systems – enable the work to transcend its expected parameters, spilling into the world beyond. Ultimately, Reactor’s work provides no immediate or easy answers, but instead an insistent demand that participants actively interpret and take responsibility for their actions and situation.