Popular opinion expresses fear that accessing radical Islamic content and connecting with extremist networks through Internet functionalities causes radicalization and recruitment to commit terrorist acts. Anecdotal evidence has been used to support this assertion. The opinion assumes the Internet creates a new path that drives radicalization and recruitment. Whether computer-mediated communication (CMC) and Internet functionalities cause individuals to radicalize has not been thoroughly studied. This thesis explores whether a correlation can be found to attribute radicalization to radicalizing content and extremist networks accessed through CMC and Internet functionalities. A framework is used to evaluate vulnerabilities identified by the psychological, sociological and social-psychological elements of radicalization against the radicalization process, personal history, and the presence of radicalizing conventional communication and extremist contact. The analysis finds three cases that may support a conclusion that Internet radicalization is possible; however, the importance of root causes and individual vulnerabilities may have a greater impact. Since some circumstances involving CMC may increase the likelihood of radicalization, the fear of Internet radicalization may be reasonable, but the number of incidents validating that fear makes the threat unlikely and appears more like a phantom menace than a real threat.