In recent years European countries have been both the targets of, and launch pads for militant jihadi attacks. This chapter focuses on the individual psycho-social vulnerabilities of those recruited into such groups, the groups themselves, their social support, and the ideologies that fuel them. It addresses the discrimination and marginalization issues facing European Muslims of immigrant descent in Europe and proposes that the lack of equal opportunity on multifarious societal arenas is one of the main factors in the creation of individual vulnerabilities that can lead to radicalization along with the recruitment strategies and ideologies that play upon these vulnerabilities. The chapter also discusses ways to counteract the effects of all this.