Radicalization to violence is a critical subset of the terrorist threat. It is the process by which individuals—often, but not always, young people—are introduced to an overtly ideological message and belief system that encourages movement from moderate, mainstream beliefs toward extreme views and, ultimately, violence.

Radical thinking is not necessarily inherently problematic. Throughout history, most political, social, and economic progress has been an outcome of some form of radicalization and the mind-set that accompanies it.