Increasing migration and forced displacement have transformed the demographic composition of schools across Europe, intensifying challenges related to social justice, inclusion, and intercultural relations. Newcomer students, particularly those from marginalised or stigmatised migrant groups, are at heightened risk of bias-based bullying and peer exclusion. Such exclusion undermines not only individual well-being but also schools’ commitments to inclusive education and democratic participation. Within this context, understanding how students respond as bystanders to intergroup exclusion is critical for developing educational strategies that promote social justice in diverse school settings.

This study addresses the following research question: How do descriptive peer group norms shape children’s and adolescents’ bystander responses to the intergroup exclusion of migrant peers, and how do these processes vary by age and different migrant groups? Specifically, the research examines exclusion involving Syrian and Ukrainian peers, two groups that have occupied distinct social, political, and media positions within European societies in recent years. By focusing on these groups, the study foregrounds the role of broader societal discourses in shaping peer dynamics within schools. This study contributes to emerging research on bystander processes in diverse school contexts by experimentally examining how peer norms interact with the social status of different migrant groups.

The study is grounded in a social–developmental and intercultural education framework, drawing particularly on the developmental intergroup perspective. This perspective conceptualises exclusion as a moral and social phenomenon shaped by group membership, power relations, and perceived norms within peer groups. From this viewpoint, bystander behaviour is not solely an individual choice but a socially negotiated action influenced by peer expectations, school norms, and wider societal narratives about inclusion and belonging. As children develop into adolescence, they become increasingly sensitive to group norms and social hierarchies, which may constrain their willingness to challenge injustice even when inclusive norms are present.

Peer group norms are central to social justice and inclusive education because they regulate what is perceived as acceptable or risky behaviour within peer cultures. Descriptive norms, beliefs about what most peers do, can either legitimise exclusion or support inclusive action. However, these norms may not operate uniformly across contexts or target groups. In societies marked by unequal power relations between migrant groups, inclusive norms may be interpreted differently depending on the perceived status of the excluded peer.

Although this study is based in the United Kingdom, its contribution is explicitly European and international in scope. Schools across Europe face comparable challenges related to migration, forced displacement, and the integration of diverse student populations. The findings therefore speak to broader debates within European educational research on social justice, intercultural education, and inclusive schooling. By linking peer norms, developmental processes, and group-based inequalities, the study contributes knowledge that is relevant for educators, policymakers, and researchers seeking to translate principles of social justice into everyday school practices.

The study employed a preregistered experimental design involving British children (n = 299, Mage = 9.48, aged 8–10) and adolescents (n = 291, Mage = 14.28, aged 13–15) recruited from schools in the South West of England. Participants were presented with a hypothetical school-based scenario designed to reflect common peer interaction contexts within European schools. Participants were asked to imagine belonging to a peer group that had formed a school club. They then read that a newcomer student, identified as either Syrian or Ukrainian, was excluded from the club by ingroup peers. Descriptive peer group norms were experimentally manipulated across three conditions: (1) help condition (most peers helped the excluded student), (2) no help condition (most peers did not help), and (3) no-information condition (no information about peer responses). After reading the scenario, participants reported their likelihood of engaging in active bystander behaviours (e.g., challenging the exclusion, encouraging inclusion) and passive bystander behaviours (e.g., ignoring the incident). Responses were measured using age-appropriate Likert-type scales. Data were analysed using factorial analyses examining main and interaction effects of age group, victim group membership, and peer group norm condition on bystander responses. This design allowed for the systematic examination of how peer group norms and victim identity interact to shape inclusive or exclusionary responses in school contexts.

The analyses revealed clear developmental differences in bystander responses to intergroup exclusion. Children were more likely than adolescents to report active bystander reactions and less likely to endorse passive responses, indicating that willingness to intervene decreases with age. This pattern suggests that adolescents may experience greater sensitivity to social risks associated with challenging peers. Peer group norms interacted with victim group membership among adolescents. In the help condition, adolescents were less likely to report active bystander reactions and more likely to report passive reactions when the excluded peer was Syrian compared to when the excluded peer was Ukrainian. Furthermore, when the victim was Syrian, adolescents were more likely to remain passive in the help condition than in both the no-help and no-information conditions. In contrast, when the victim was Ukrainian, adolescents were more likely to report passive bystander reactions in the no-information condition than in the help condition. These findings indicate that descriptive peer group norms do not operate uniformly across contexts. While helping norms were associated with reduced passivity toward Ukrainian peers, they were less effective in promoting active intervention when the excluded peer was Syrian. This suggests that adolescents may interpret peer norms in relation to broader social meanings attached to different groups, rather than applying inclusive norms consistently. Overall, the results highlight the importance of considering developmental stage, group norms and group membership when examining bystander responses to intergroup exclusion. They suggest that as children move into adolescence, peer group norms and perceived social hierarchies play an increasingly influential role in shaping responses to bias-based exclusion. The findings underline the need for educational approaches that recognise how peer norms and group status jointly influence students’ willingness to challenge exclusion in school settings. These findings point to the value of further research examining how school-based norm-setting practices may impact students from diverse migrant backgrounds.

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