Extreme political attitudes have gained more and more scientific attention with the advent of populist parties in many Western countries (see Lewis et al., 2018). Whereas many researchers suggested either societal (e.g., Neumann, 2017) or individual risk factors for radicalization leading to extremism (for an overview, see Borum, 2014), the present study builds on recent models that emphasize the importance of person-situation interactions (e.g., Kruglanski et al., 2014) and sheds light on one individual difference variable that can both be affected by and affect social interactions:The individual propensity to perceive threat to one's own social identity (see Stürmer et al., 2019).Intergroup Threat Theory (ITT; Stephan et al., 2016;Stephan & Stephan, 2000) postulates an individual ingroup favoritism resulting from the benefits that a social group offers to a person, such as social support, a sense of belonging, or a set of common norms and values (e.g., Everett et al., 2015). Therefore, outgroups are often perceived as a threat to one's own ingroup. According to Stephan et al. (2016), this intergroup threat (IT) can be either realistic or symbolic (i.e., calling into question the ideology or belief system of the ingroup) and affect the individual itself as well as the group