The Counter-Terrorism and Security Act 2015 places a specific duty on clearly identified actors to prevent terrorism. This paper adopts a poststructuralist approach to deconstruct the Prevent Duty's ideology and discourse. Using Foucauldian terminology, Prevent is conceptualised as a proactive "dispositif" to manage the risk of extremism in the UK, in that it is an 'ensemble of discourses,' 'regulatory decisions' and 'moral positions' (Foucault, 1980: 194) that constitute a complex system of response to the threat of terrorism. A globalised state of (in)security is posited as a major influence for Prevent's inception. The formulation of the policy text is underpinned by the neoliberal "governmentality" of the Big Society. The paper problematises its implementation in the education sector through the analysis of the 'duty' to promote British values in the classroom and the expectation of 'preventing people from being drawn into terrorism' (HM Government, 2011; 2019). It concludes that the "dispositif" is driven by principles of human rights and proactivity, however, it has been largely misinterpreted due to lack of clarity and the assumption of shared values.