AbstractViolent extremism is on the rise again across the globe (STARTS, 2018). In this dissertation, we propose an integrative model of intergroup co-radicalization processes to understand those phenomena and apply to the study of the post-terror attack context in France. Drawing upon social identity and existential perspectives, we demonstrate how terror attacks can trigger political violence against minorities in France (under the cover of an extreme secular ideology) which in return generates more support for ISIS and intentions to engage in political violence among minority members exposed to discrimination, further feeding the ‘vicious circle’. Consistent with both perspectives, anomia (feelings of powerlessness, meaninglessness, self-estrangement, normlessness and social-isolation) was found to be a consistent predictor of violent extremism and a mediator of threat’s effects on socio-political attitudes. This lead us to propose an new model to understand ideological extremization after death-related threats (such as terror attacks) and to discuss the potential usefulness of integrating anomia to current social-psychological theories of violent extremism (e.g. Significance Quest, Kruglanski & Orehek, 2011). After discussing the practical implications of these findings in terms of policy recommendations, we conclude that anomia, by bridging the gap between social identity and existential perspectives could lead to the emergence of a true social-existential take the psychology of violent extremism.