This paper analyses how British counter-radicalisation policy, and the Channel project in particular, constitutes individuals who are vulnerable to radicalisation as visible, producing them as subjects of intervention. It thus asks, how can potential terrorists be identified and made knowable? The paper first argues that to understand Channel, it is crucial to develop a conceptual account of the security politics of (in)visibilisation that draws attention to the ways in which security regimes can, at times, function primarily through the production of regimes of (in)visibility. Utilising this approach, the paper focusses on the role of 'indicators' as a technology of (in)visibilisation, producing certain subjects as newly visibilised as threatening: a role that is central to the functioning of Channel. Yet such a production is political. In bringing together a politics of care and a politics of identity, it is a regime of (in)visibility that produces new sites of intervention, contains significant potential consequences for the expression of certain identities, and raises new and troubling possibilities for how contemporary life may be secured.