The article examines the role of NGOs in the politicisation of EU security. The focus of the empirical analysis lies on the field of EU counter-terrorism. The cases selected are two different types of legal acts, adopted in the aftermath of serious terrorist attacks in EU member states: The EU data retention directive and the EU passenger name record (PNR) directive. These policies present intrusiveness and relevance for Brussels-based and national civil rights NGOs since they both aim to touch upon individual liberties, like privacy rights or the right to protect personal data. The article goes further by opening up the black box of politicisation. It does so by assuming that politicisation is characterised by a certain level of salience, actor range and polarisation. The paper links politicisation literature to research on the influence of interest groups that are discussing, for example, voice, access or litigation as strategies. Therewith, the paper contributes to the scientific debate on politicisation in two ways: First, it sheds light on the so far disregarded role of NGOs in politicisation. Second, it builds a bridge to interest group literature by examining repertoires of NGOs in politicisation.