It is a human fundamental to desire to be valued, loved and respected--to be significant. Social exclusion induce significance loss which elicits a 'quest for significance'--the search for opportunities to re-gain significance. The present article establishes this relation in a laboratory experiment (N = 71, mean age = 28, SD = 10.42, 65% women, 35% men), showing that socially excluded individuals who are subsequently included by a radical group, adapt their attitudes in line with this group. We use a modified version of the well-known paradigm 'Cyberball' to elicit the quest for significance. The results show that when experiencing social exclusion, highly rejection sensitive individuals tend to adapt to the radical group's opinions. The results are important, highlighting a mechanism in the radicalization process and the importance of taking social factors into account in this process.