Terrorism perpetrated by Muslims has become a global phenomenon that has significantly impacted upon nations throughout the world. Radicalization is the process of gradually subscribing to a violent ideology espousing terrorism. Existing research on the radicalization process has involved convicted terrorists and the study of their lives retrospectively to identify risk factors, triggers and catalysts for the emergence of radicalization. Models have been developed and theories have been applied to explain the process of radicalization. This review will summarize literature on radicalization and identify gaps in existing research. For example, radicalization has not been directly studied in its early stages, has not involved comparison with non-radical Muslims and, more specifically, the mechanics of ideological conversion has not been well researched.