This thesis employs a critical discourse analysis approach to examine how different actors negotiate the boundaries of what can (and cannot) be defined as ‘radicalisation’. The study analysed two major policy documents, Kenya’s National Strategy for Countering Violent Extremism and the Mombasa County Action Plan for Preventing and Countering Violent Extremism (PCVE); 57 speeches and statements of Kenyan president Kenyatta; 474 press articles; 19 interviews with PCVE practitioners; and two focus groups conducted with 11 young people in Mombasa. I found that Kenya's ‘radicalisation’ discourse draws on diverse discursive resources of legitimation and representation to advance psychosocial, cultural, theological and politico-economic themes. Policy texts, speeches and the press attributed ‘radicalisation’ to psychosocial, cultural and theological explanations while discrediting the socio-economic and political contexts facilitating ‘radicalisation’. These themes composed national discourses and were (de)legitimated through authorisation and moral evaluation strategies. In contrast, practitioners and youth often but not exclusively described ‘radicalisation’ as an outcome of cultural, social and political injustices. These local discourses were justified and (de)legitimated through moral evaluation, particularly, analogies. National and local discourses categorised young people in contradictory ways. On the one hand, genericisation, classification and aggregation strategies represented all young people as victims and ‘at-risk’ of becoming violent due to their socio-economic and cultural contexts. On the other hand, nomination, genericisation, indetermination, classification, differentiation, and functionalisation also characterised youth and specific young people as ‘a dangerous Other’ threatening Kenya’s stability, peace and prosperity. Young people’s experiences and perceptions blur the victim—dangerous binary highlighting how aspects of vulnerability and youth exercise of agency in uncertain socio-economic and cultural contexts coexist. They challenge universal knowledge claims and demonstrate that the subaltern knows their situation better; thus, their accounts need to be taken seriously. The texts under analysis were produced in different domains, but they drew on elements and discourses from each other, thus showing complex patterns of discourse continuity and transformations. This research contributes by showing that discourses are products and productive of multiple practices of power (power relations) and particular representations of youth as a social category that make up the boundaries of what can be intelligibly considered as ‘radicalisation’ and PCVE. This was particularly possible because of the condition of linearity which enabled Kenya’s disparate categories of past and contemporary events to be viewed and depicted as falling within a single trajectory. This research shows parallels between the colonial and post-independent state discourses on ‘radicalisation’ and ideas of who constitutes a ‘radical’. It is almost entirely the category youth which is often a constellation of a wide range of ideas, situations and circumstances that allows the different security stakeholders (local and global ones) to agree that ‘radicalisation’ is a ‘youth issue’ without having to unpack what they each mean by ‘youth’ or even ‘radicalisation’. This research underscores that it is the amorphous discourse of youth that allows ‘radicalisation’ and PCVE to first, exist and second, reinforce paternalistic logics under the guise of protecting young people.