This study seeks to explore the issue of radicalization and extremist activity in the prison environment. Using a combination of prison theory, historical examples and contemporary open source material, this report seeks to identify lessons from previous instances of dealing with extremist prisoners. It is envisaged that these lessons may provide insights about the challenges posed by the increasing number of violent imprisoned jihadists. This report draws a number of conclusions about what is and what is not known about the nature and extent of the problem. It highlights a number of areas that appear to require additional research and exploration.