<p>The present study builds on the Significance Quest Theory to investigate the mechanisms that render individuals susceptible to violent extremism. Through a survey study, we examined how feelings of (in)significance, conceptualized as the Self-Determination Theory’s needs for autonomy, relatedness, and competence, relate to violent extremist attitudes. We tested models for both need frustration and satisfaction, including aggression as mediator, and simple knowledge beliefs and empathic concern as moderators. Our findings demonstrate that relatedness frustration is a prominent risk factor for violent extremism, whereas relatedness satisfaction serves as a protective factor. The unique impact of autonomy and competence were relatively limited. Furthermore, increased levels of aggression partly explained the relationship between relatedness frustration and violent extremism, and simple knowledge beliefs and empathic concern respectively strengthened and weakened the relationship between aggression and violent extremism. These findings help to understand how feelings of insignificance can instill a susceptibility to violent extremism, and how addressing relatedness may be key for deradicalization programs.</p>