A new model of radicalization has appeared in Western countries since the 2010s. However, few empirical data are available to interpret the profiles of European young people who have embraced radical Islamism. Mixing qualitative/quantitative approaches, the present study is the first to explore their motives for radicalization, as well as how characteristics at baseline predicted their status at follow-up (FU). In 2014-2015, 150 individuals (mean age: 19.82 years; 101 (67.3%) females; 100 (67%) Muslim converts) were followed-up prospectively by the Centre de Prévention contre les Dérives Sectaires liées à l’Islam (CPDSI) until September 2016. Using a multiple correspondence analysis, we found that eight motivational dimensions (interest in violence; feelings of depression, responsibility, uncertainty or loneliness; experience of abuse; issues with sexuality; and poor insight) combining in eight statistical factors drove individuals towards radicalization. At FU, 95(63%) were no longer radicalized, 21(14%) were disengaged, 19(13%) were still radicalized, and 15(10%) had reached the Islamic State. Univariate and multivariate analyses found some protective factors defining individuals with developmental vulnerabilities that can be encountered in many psychopathologies. In addition, multivariate models showed that worse status at FU was predicted by being married, having married parents, having attempted to radicalize other relatives, and having a close friend or relative imprisoned before radicalization. We conclude that multidimensional efforts to de-radicalize young people are efficient, although a worse prognosis is associated with neighborhood/proximal phenomena. Prevention should target these local/proximal contexts to further prevent radicalization.