The Prevent Duty mandates education providers to address young people both as vulnerable to radicalisation and as (potentially) resilient. This paper argues that interventions designed to address vulnerability are problematic, as they tend to adopt the logic of safeguarding – a familiar mindset for professionals working with young people – while also extending practices of surveillance. As well as this safeguarding/surveillance nexus, however, the Duty offers openings for resilience-focused school-based interventions, which can assist young people’s development into active citizenship. Drawing on Chantal Mouffe’s distinction between “agonism” and “antagonism”, I will argue that the Duty endorses interventions to build resilience grounded in the effective capacity for citizenship, understood as enabling individuals both to take sides in (“agonistic”) political debate and to engage with the criteria for excluding certain (“antagonistic”) positions from political legitimacy. Supporting this argument, findings from mixed-methods research conducted in secondary schools suggest that training delivered under the Duty can offer significant gains in self-confidence and political engagement, and hence in effective citizenship and resilience to extremist messaging.