The adolescent peer group is an important socialisation environment, and the sense of belonging to this group contributes to many positive outcomes for adolescents. Given the important developmental role of peer groups, it is important to recognise that there are environments in which it is difficult to achieve positive peer interactions and group belonging, such as institutional care. Research on different aspects of group processes with adolescents in care settings has shown the importance of good peer relationships (Huefner et al., 2018; Sonderman et al., 2020) and identification with the group (Magalhães and Calheiros, 2015a; Magalhães et al., 2016) for achieving positive outcomes during their stay in the care setting. In addition, this group of adolescents is often negatively valued and discriminated against by society due to the separation from their own families, and the multiple personal and social risks. Therefore, the care environment should offer adolescents as many opportunities as possible to overcome negative social identities resulting from their social position. Social identity theory (Tajfel & Turner, 1979) and The Rejection-Identification Model (Branscombe et al., 1999), which assumes that identification with a discriminated group can mitigate the negative effects between perceived discrimination and subjective well-being, form the theoretical basis for this study. The literature shows that the model has been tested several times on very different groups and that it was confirmed, partially confirmed, or not confirmed depending on the type of group. The model has not yet been researched or confirmed for a group of adolescents who are placed in institutional care. For this group, only individual studies on constructs of the model can be found (e.g. on group identification or perceived discrimination). The literature also shows that support from group members is also an important element in confirming the model. Therefore, this construct is included in this study in order to clarify the relationships of the model in this population. Aim and study design The aim of this study was to investigate the group identification of adolescents in institutional care. For this purpose, a mixed-method approach was used, that is, exploratory sequential design, in which first qualitative and then quantitative are collected. The first phase of the study involved qualitative research with the aim of gaining a deeper understanding of the characteristics and outcomes of group identification in adolescents in institutional care and developing measurement tools. The second phase of the research involved doing preliminary research, with the aim of verifying the developed and adapted measurement instruments. The third phase of the research was to conduct quantitative research with the aim of testing the Rejection-Identification Model, which is based on the assumption that group identification mitigates the negative effects between perceived discrimination and subjective well-being. The analysis draws conclusions based on the qualitative and quantitative data. Methodology A total of 30 adolescents participated in the qualitative phase. The data was collected using the focus group method. A total of 5 focus groups were conducted in different institutions. The data was analysed using thematic analysis. In addition, two measurement instruments for the construct of perceived discrimination and life satisfaction were developed on the basis of the collected data. A total of 107 young people took part in the quantitative preliminary phase. After factor analysis and the necessary changes to the content, the versions of the measurement instruments to be used in the third phase of the study were finalised. A total of 216 adolescents participated in the third phase. The measurement instruments used in this phase were the Life Satisfaction Scale and the Perceived Discrimination Scale (created for this research), the Group Identification Scale (Magalhães and Calheiros, 2015a), the Child Adolescence Social Support Scale (Malecki et al., 2019) and the State Self-Esteem Scale (Heatherton and Polivy, 1991). The adolescents completed the instruments individually. They needed a total of 10 minutes to complete the questionnaire. The data analysis comprised a descriptive analysis, a hierarchical regression analysis and a test of mediation effects. All phases of data collection took place between July 2022 and June 2023. Approval to conduct the study was granted by the Ethics Committee of the Faculty of Education and Rehabilitation Sciences of the University of Zagreb. Results In the qualitative part of the study, the results show that the experience of discrimination due to a stay in institutional care is individual and rare. The adolescents most frequently experience discrimination in their relationships with peers outside or inside the institution as well as in close friendships and intimate relationships. It was also found that certain subgroups experience higher levels of discrimination in care, namely adolescents with behavioural problems and those belonging to the Roma national minority. Adolescents feel institutional care is negatively perceived by society, and fear that it affects some of their relationships, and limits their life chances and opportunities. Peer groups in care have their own specific peer culture and norms, and relationships are often situational and discontinuous. Identification with the group is seen as a protective factor for living together. However, adolescents feel little commitment to the group in institutional care and perceive themselves as individuals in comparison to other peers. Commitment is a bond existing between the individual members of the group or in peer subgroups. Group identification is achieved through commitment and the provision of social support. There is a positive perception of the peer group in the institution. Social support from peers includes understanding and emotional support, sharing similar interests as well as help and learning life skills. Adolescents express satisfaction with their lives in various areas, with the lowest satisfaction with themselves and current life circumstances. Peer relationships are complex and depend on various circumstances, including the context of peer group and the individual characteristics of adolescents. In the quantitative part of the study, the results show that the tested The Rejection-Identification Model (Branscombe et al., 1999) was not confirmed in the population of adolescents in institutional care. Only the dimension of commitment and group evaluation was found to be a partial mediator in the relationship between perceived discrimination and stated self-esteem, in that higher perceived discrimination was associated with lower commitment and group evaluation, and lower commitment and group evaluation was associated with lower self-esteem. It was also expected that group identification would be a significant mediator in the relationship between group identification and life satisfaction, but it turned out that there were no significant mediating effects of any dimension of group identification in this relationship. The results show a direct negative effect of perceived discrimination on state self-esteem and life satisfaction. As for testing the mediating role of social support in the model, the results show that social support was a significant and partial mediator only in the relationship between one dimension of group identification – commitment and group evaluation – and life satisfaction, in that higher commitment and group evaluation was associated with higher social support, and higher social support was associated with higher life satisfaction, which was expected in the hypothesis. Social support did not prove to be a significant mediator in the relationship between group identification and state self-esteem. Conclusion The integration of the results shows that the findings complement each other and provide information for a comprehensive understanding of the research topic. Perceived discrimination is not very common and mostly takes place in peer groups outside the institution (school and local community), inside institutions or in intimate relationships. It is difficult for adolescent in care to live with the expectation that they will be discriminated because others have a negative image of institutional care and the children and young people who are placed there. This data is particularly concerning given that quantitative research data has shown that perceived discrimination has a direct negative impact on the subjective well-being of young people in care, in a way that is negatively related to state self-esteem and life satisfaction. In terms of the dimensions of group identification, commitment and group evaluation emerged as an important dimension for achieving positive outcomes. Self-categorisation appears to be related to some extent to the negative identity ascribed to institutional care, and adolescents feel different from other members of the group. Considering that the peer group in care is discriminated in a certain way, social support plays an important role in achieving positive relationships and creating an emotional connection. Life satisfaction is related to life circumstances in general, relationships with other peers, and the characteristics of peer relationships in a particular institution. The research findings offer new insights into group processes in institutional care and offer scope for future research in this area. The results also provide important empirical findings that can be used to improve the quality of care, reduce discrimination against this group of adolescents and strengthen the role of the peer group in subjective well-being.