Book excerpt: Radio produced and broadcast behind prison walls is redefining traditional meanings of ‘public service broadcasting’ and disrupting traditional power structures within the prison system. Focusing on one of the most interesting developments in UK prisons over the past 10 years, this book examines the early history of the Prison Radio Association and the formation of the first national radio station for prisoners. Highlighting the enduring importance of social values in broadcasting this book shows how radio can be used as a powerful force for social change. It will be of interest to those involved in media, criminal justice and social activism.