This article discusses individual mobilization to extremist violence from the perspective of a researcher and analyst, exploring what we know about the psychological and social factors motivating young people to join extremist groups and how that knowledge relates to the recruitment of individuals into ISIS. The biggest threat to the West, at least for now, is not core ISIS (or any jihadi group operating in the Middle East and North Africa region), but Westerners who self-mobilize for attacks at home or who return, trained to fight, from the “jihad” abroad. Finally, the article suggests specific ways for governments to respond to this threat, noting the limits of what government can do, and arguing that they join forces with the private sector. Mobilization to extremism must be addressed with broad, multi-institutional social strategies.