Introduction: People's tendency to perceive threats in other groups, even when no actual threat exists, aligns with the fact that humans are social beings who highly value their own groups, which fulfil their need for belonging and help their understanding of the complex social world and their position within it. However, the perception of threat can severely damage social relationships, making it crucial to understand why and how it occurs in specific contexts. Intergroup threat emerges when the behaviours, beliefs, or characteristics of one group pose a threat to the goals or well-being of another group (Stephan & Stephan, 2018). Research on intergroup threat has evolved from highlighting the significance of specific threat forms on intergroup relations to an integrated threat theory that consolidates the propositions of earlier theories and emphasizes that the perception of a threat from an out-group is crucial to negative intergroup attitudes and (intentions for) behaviours, while actual threat presence may or may not be present (Croucher, 2018; Riek et al., 2006; Stephan & Stephan, 2000). Threat can manifest in various forms, including realistic and symbolic threat, as well as intergroup anxiety (W. G. Stephan et al., 2008). Research findings on intergroup threat confirm that individuals who lack contact experience with members of another group are more prone to perceiving threat, while more frequent contact is negatively associated with the perception of both realistic and symbolic threat (Tropp & Pettigrew, 2000; Velasco González et al., 2008). Intergroup friendships can be particularly effective in reducing the perception of threat as they satisfy majority of optimal conditions for the positive effects of contact: they involve cooperation and common goals, endure over extended time periods and across various situations, and foster feelings of closeness, trust, and equality (Pettigrew, 1997; Pettigrew et al., 2007; Pettigrew & Tropp, 2011; Pettigrew et al., 2011; Tropp, 2008). Even when direct intergroup friendships are not feasible, extended intergroup friendships have been shown to lead to more positive intergroup attitudes. While direct forms of contact generally have stronger effects on the attitudes of majority group members, the effects of extended intergroup friendships should be equally potent among minority and majority group members (Feddes et al., 2009; Gómez et al., 2011; Tropp & Pettigrew, 2005). However, studies on the impact of intergroup friendship on intergroup relations often only examine the role of intergroup anxiety (Turner, Hewstone & Voci, 2007; Turner, Hewstone, Voci, Paolini & Christ, 2007; Turner & Feddes, 2011), neglecting other types of threat presented in intergroup threat theory (Stephan & Stephan, 2018). Another significant antecedent of perceived intergroup threat is an individual's level of identification with their own group, as individuals must feel sufficiently connected to their group to perceive a threat directed toward it (Tajfel & Turner, 1986). However, in the context of ethnic groups, it is essential to consider how an individual is tied to their own ethnic group, as different forms of attachment can have diverse intergroup consequences (Brewer, 2007; Roccas et al., 2006). Affection and love for one's own people ("pure" ethnic identity) should be distinguished from (ethno)nationalism, which implies the superiority of one ethnic group over another (Mummendey et al., 2001; Schatz et al., 1999). Few studies on intergroup threat have taken into account various forms of group attachment (e.g., Dimitrova et al., 2015; Jelić et al., 2020), leaving room for different interpretations of the findings. Regarding research on perceived intergroup threat in Croatia, aside from frequent studies in Vukovar (Čorkalo Biruški & Ajduković, 2007, 2008a, 2008b, 2009, 2012), there is a scarcity of research on the determinants of intergroup threat from indigenous minorities in different contexts in Croatia and consequently, their reactions to it. Intergroup threat has mostly been examined concerning immigrants and asylum seekers (e.g., Kalebić Maglica et al., 2018; Kumpes, 2018; Župarić-Iljić & Gregurović, 2013). However, it is not justified to equate immigrants with ethnic groups that have been living in Croatia for decades or centuries and have specific constitutional rights and status in society (Kymlicka, 1995). Given that perceived threats emerge during intergroup interactions, research on threat in real conditions of coexistence between two or more groups, such as multi-ethnic communities, is of greatest importance. A methodological limitation in previous studies of intergroup threat within the assumed intergroup threat model (Stephan & Stephan, 2000; W. G. Stephan & Renfro, 2002) is the prevalence of cross-sectional correlational research designs, where all variables, that is assumed predictors, mediators and outcomes, are measured at a single point in time. Additionally, most research has focused on the consequences of perceived intergroup threat, which leaves a gap in longitudinal research of most significant antecedents of perceived intergroup threat, which are various forms of intergroup contact and ingroup identification. Moreover, research has primarily focused on the perception of threats among members of the majority group (e.g., Ljujić et al., 2012; Oliver & Wong, 2003; Velasco González et al., 2008), although there is an increasing recognition of the importance of considering the experiences of minority groups (e.g., Birtel et al., 2020; Jelić et al., 2020; Löw Stanić, 2014; Vedder et al., 2016; Tausch et al., 2009). Nonetheless, few studies, like this one, combine a longitudinal approach with the inclusion of participants from various ethnic groups and data collection in a representative sample, within a multi-ethnic community. The aim of this study was to examine the role of different forms of intergroup contact and ingroup identification in predicting various forms of intergroup threat, according to the intergroup threat theory (Stephan & Stephan, 2000; W. G. Stephan et al., 2002), among adolescents from multi-ethnic communities in Croatia. We investigated the longitudinal effects of direct and extended interethnic friendships, ethnic identity, and ethnonationalism on the perception of intergroup threat via two research questions. Within both research questions, we also explored whether the presumed relationships were moderated by the majority-minority group status and the multi-ethnic research context. Methodology: This research was a part of a broader research project titled "Integration processes of majority and minorities in ethnically mixed communities: The role of intergroup contact, perceived threat, and social norms – IntegraNorm," which was conducted with parents and students from elementary and high schools in four multiethnic communities in Croatia. The students participated in the study at two time points, providing longitudinal data, while parental data were only collected at the first measurement point and are not relevant to this study. The targeted sample of this research were students belonging to ethnic minority groups in Croatia, who are educated in their mother tongue and script according to Model A, as well as their peers, members of the ethnic majority – Croats, who are educated in the Croatian language and script in the same communities where schools in the minority language are located or in their immediate vicinity. The research was conducted at two time points, T1 and T2. The first data collection took place during the winter and spring of 2017, with the second data collection occurring one year later. In both time points, questionnaires were administered during regular classes within a one school hour (45 minutes). The questionnaires intended for majority and minority students were identical, except that for majority students, the content of intergroup variables was directed toward members of the relevant ethnic minority in each context, while all minority students assessed their Croatian peers. Depending on whether children attended classes where instruction primarily took place in the minority or majority language, they were assigned the status of ethnic minority or majority. The total longitudinal sample consisted of 852 students, of which 45.5% were male, and the age range at the first measurement point was from 12 to 20 years, M = 15.69, SD = 1.77. Results and conclusion: After conducting all preliminary analyses and defining appropriate measurement models, we proceeded to test longitudinal autoregressive cross-lagged panel models (ARCLPM) using linear structural equation modeling (SEM) methodology. To further evaluate the possible moderating effects of the participants’ group status and context in the cross-lagged models, a multigroup procedure was established. Multigroup analysis is recommended approach when the moderator is a dichotomous variable (Little, 2013). The results did not corroborate the predictions regarding the predictive role of direct and extended intergroup friendships and ethnic identification in the perception of intergroup threat. We only corroborated one hypothesized effect, that is we found that those participants with a stronger ethnonationalism at T1 experienced higher levels of symbolic threat at T2. Individuals with a developed ethnonationalistic identity tend to base their self-esteem and group worth on comparisons with other relevant groups with whom they are in constant competition. This stronger identity can lead to greater sensitivity to realistic or symbolic threats, depending on the narrative of the ingroup about the outgroup, and it seems that in our context the more prominent distinguishing features are at the level of identity (language, origin, customs), and not resources. Other significant effects suggest a reciprocal relationship between identity and the perception of threat. We found that a stronger perception of symbolic threat at T1 led to greater attachment to one's ethnic group at T2, just as intergroup anxiety at T1 increased ethnonationalistic sentiments at T2. The effect of intergroup anxiety was the strongest effect and, while numerous studies have confirmed the relationship between intergroup anxiety and intergroup contact (Binder et al., 2009; Pettigrew & Hewstone, 2017; Vedder et al., 2017), it proved more significant for ethnonationalism in this study. Ethnonationalism might serve as a rationalization for adolescents from multiethnic environments to cope with their experienced intergroup anxiety. In addition to the affective type of threat, the perception of a more cognitive symbolic threat also led to stronger ingroup identification. Conceptually, symbolic threat arises when the outgroup is perceived as a threat to the identity and worldview of ingroup. Thus, it seems logical that one way of preserving this threatened identity is by increasing ingroup attachment. In line with the threat-identity model (Schmid & Muldoon, 2015), our results suggest that the negative effects of perceived intergroup anxiety and symbolic threat can be partially mitigated by increased ingroup identification. In the relationship between intergroup friendships and the perception of intergroup threats, we confirmed a reverse causation model with a significant negative effect of the perceived realistic intergroup threat on direct interethnic friendships. This finding implies that a higher perception of realistic intergroup threat at T1 predicts fewer direct interethnic contacts at T2 among adolescents in multiethnic communities. The perceived realistic threat, as operationalized in this study, includes the perception that the outgroup enjoys more privileges and rights, advantages in employment, greater educational opportunities, an easier path through the educational system, and better conditions in schools. Thus, the perception of an unjust resource distribution reduces the likelihood of intergroup friendships. We can explain this result from the perspective of the social identity approach (Tajfel & Turner, 1979), which dictates that individuals strive to maintain a positive social identity by favouring their ingroup and, under certain conditions, distancing themselves from other groups. One of these conditions includes the perception of a real intergroup threat, to which groups react by closing into their ethnic circles, possibly to express intragroup solidarity and to distance themselves from the source of the threat. Contrary to our expectations, we did not confirm the assumed moderating effects of group status or context. In other words, we demonstrated that the relationships between variables operate in the same way across groups, regardless of status and context. It is possible that adolescents from multiethnic communities are similar to each other; however, further research is needed to verify the investigated relationships and reach unequivocal conclusions. There is a possibility that we failed to capture existing differences among groups and contexts due to certain methodological limitations mentioned in the paper. In conclusion, this paper offers valuable insights into the intergroup relationships of adolescents in multiethnic environments and the role of threat perception in these dynamics. We hope this paper will stimulate new, methodologically even stronger research that will provide a more comprehensive understanding of risk factors for the emergence of intergroup threat and its negative (and positive) consequences.