Using France as a case study, contributors from around the world explore the factors that create violent extremists, including criminogenic needs, violence-supportive cognition, religious beliefs, identity uncertainty or fusion, the quest for significance, and social and political influences. They present a multidisciplinary and evidenced-based analysis of how and why violent extremism has reappeared as a contemporary issue and provide theoretical and practical approaches to responding to and, when possible, intervening, using deradicalization programs, deterrent and preventive legislations, prison segregation, and permanent monitoring.