One of the crucial issues of radicalism lately has been the involvement of family members in acts of terrorism. But families and their role in the radicalization process have not yet received proper attention from researchers, despite the growing interest shown by policy makers in several countries. This chapter provides an overview of the role of families in radicalization. Both research literature and policy and practice consider families as a potential risk of radicalization, as well as a source of protection and rehabilitation. Finally, the chapter highlights the importance of prevention, even a family level. Families may not notice change in family members who are undergoing a process of radicalization and specifically youngster may be at risk of radicalization, because of the long time they spend online.