The global resurgence of violent extremism punctuated by recent acts of politically motivated violence necessitates a detailed examination of the factors that contribute to the radicalization process. Here, we argue that relative deprivation, or the perception that one’s in-group is unfairly deprived of material or symbolic goods relative to other groups, often elicits support for violent extremism. Because relative deprivation theory emphasizes perceived, rather than actual, experiences of injustice, the concept helps explain why members of both structurally disadvantaged and advantaged groups sometimes turn to violent extremism – especially when they believe that their in-group cannot redress their perceived grievances through normative mechanisms (i.e., when group efficacy is low). After demonstrating that relative deprivation can foster support for extremist violence and introducing an integrative model of group-based relative deprivation and violent extremism, we propose solutions to the growing threat of radicalization including the need to (a) reduce inequality, (b) develop productive ways for the disenfranchised to establish meaning in their life, (c) foster belongingness, and (d) build inclusive democracies that provide legal means to redress real or perceived grievances. By taking such proactive measures, practitioners and policymakers can mitigate the threat of violent extremism and make the world a safer place.