Counter-extremism is the most dynamic part of UK counterterrorism policy. This article examines Prevent, the flagship counter-extremism programme, through a state-theoretical lens. It addresses questions of state institutionality, state power, and state-society relations. It argues that counter-extremism aims to avert the possibility of a political future by repressing the formation of non-liberal political subjectivities. To achieve this, Prevent divides society along political lines; aligns welfare institutions with the security apparatus; mobilises society in a security endeavour; exercises an authoritarian ‘pastoral’ power; replaces trust with generalised suspicion; and construes subjectivities without capacity for historical agency. Therefore, Prevent is a political paradox: an anti-liberal project aiming to secure and perpetuate liberalism.