This Research Note presents a framework for mapping the radicalization and mobilization pathways of radicalized Western Muslims (who represent a small proportion of their countries’ overall Muslim populations) into (1) becoming foreign fighters in Syria to engage in insurgent and terrorist activities or to decide to return to carry out such attacks in their home countries, (2) becoming radicalized in the West by these jihadist organizations and their local surrogates to carry out terrorist attacks in their own home countries without leaving them, and, to validate the framework’s preemptive counter-measures, (3) becoming radicalized into deciding to become jihadi fighters in Syria but being prevented from traveling there either at border crossing points, such as Turkey, or through other preventative measures at various stages of their mobilization in their home countries. To accomplish these objectives, the framework presents five categories that characterize such trajectories, which are broken down into thirteen factors, with each factor marked by critical points for preemptive intervention by government security services.