A convergence between vulnerability, radicalisation and children has been framed as an emergent category of abuse: “childhood radicalisation”. Focusing on the UK PREVENT programme, this paper explores the ways children have become interrelated with counter-radicalisation. While PREVENT engages with people of all ages, Home Office data indicates children are a target group. This approach has been consolidated through the Counter-Terrorism and Security Act (2015) which legislates PREVENT as safeguarding. Inspired by Ernst Bloch’s “ontology-of-the-not-yet”, this article draws upon critical geographies of “hope” as a theoretical tool to unpack PREVENT. I explore the productive power of PREVENT in catalysing “hopeful” forms of subjectivity; specifically, the pedagogy of PREVENT, and de-radicalisation through Channel. The article then extends Bloch’s original apparatus to examine the ways hope acts as an assemblage of affects to enact practices of control. It is the reciprocal influence of hope, fear and anticipatory security that helps illuminate how PREVENT makes visible, and thus regulates, processes of becoming. The article traverses disciplines encompassing criminology, critical geography, critical international relations, and critical terrorism studies. This inter-disciplinary approach usefully captures PREVENT in terms of performativity, anticipatory security and the figuration of the child.