This article explores UK Parliamentary debate around the proscription - or banning - of terrorist organisations. It argues that these debates are usefully conceptualised as a form of political ritual organised around a core script, established participant roles, a shared respect for the performance of democracy and a predictable outcome. Taking these ritualistic aspects seriously extends research on proscription by highlighting the importance of the procedures through which such organisations are produced as requiring exclusion from the UK's body politic. The article therefore makes three contributions. First, it provides a sustained empirical analysis of data from every relevant UK Parliamentary debate on proscription between 2001 and 2014. Second, it moves academic debate on proscription beyond questions of the power's effectiveness and legitimacy. And, third, it contributes to contemporary work on political ritual by offering a new heuristic for the analysis thereof centred on four dimensions: orchestration, constitutivity, sedimentation and performativity.