My thesis uses an 'ethnographic' approach to explore the complexities of radicalisation within Hizb ut-Tahrir (HT), a clandestine radical Islamist organisation. At the heart of this thesis is the issue of radicalisation: that is, how some young British Muslims become radicalised and why they join HT. After spending several years interacting with HT radicals, I was able to interpret their social world, enabling me to map out some of the personal trajectories into the group. There appears to be a reciprocal relationship between the radical and the social field that provides a pretext for radicalisation. My reference points were several powerful and insightful biographical accounts of members of HT. I chose these case histories, while interacting with HT members in their natural settings, because they exemplify some important theoretical points and provided a rich source of narrative concerning the pathway into Islamic radicalism. The results of my research indicated that common traits existed in certain individuals, especially prior to joining HT. I identified a host of recurring characteristics amongst most of the respondents. Activists were greatly influenced by, and matured in reaction to, adverse social interactions experienced during their early life cycle development. Members had not formed stable connections with their social environments, which would suggest that respondents' current identities are the outcome of a failure to integrate within the social context. In this respect, the members needed the group to gain a sense of belonging. Also, HT has managed to attract a disproportionate number of middle-class recruits. This unbalanced stratification has resulted in the emergence of a homogeneous sub-group, which is uniformly represented by young, middle-class, South Asians. Therefore, the process of radicalisation within HT has distinct psychological and sociological characteristics that make it definable: a UK member profile can be formulated, defining the key features before and after radicalisation.