Investigating the appeal of the group Hizb ut-Tahrir (HT), the study expands on why non-violent radical forms of Islam still attract segments of Muslim communities in the West. Being one of the few comprehensive studies on HT, this book discusses how this Islamist group advocate for the caliphate and for the implementation of shari’a but also reject violence as a tool to achieve these goals. Through interviews with current HT members, observation at HT-sponsored events and social media analysis, this book leads the reader into the world of vocal radical Islamist groups, exploring their goals and activities in Western states, with a special focus on the UK and Australia. In fact, as many other non-violent Islamist groups, HT represent the choice of all those individuals who might share Islamist arguments but who reject the use of violence. Given their non-violent nature, vocal radicals are mostly free to operate in the Western world, attracting new members, conducting a relentless campaign against the "West as a system" and representing a serious source of concern not only for national authorities but for the broader Muslim community. This book stands as an original publication and paves the way to a new area of study crossing sociology, Islamic studies and political sciences. This book is one of the few contributions on vocal and radical Islamism to date.