SUMMARY Introduction Sex and gender are understood as two related but separate constructs. Sex refers to the biological and anatomical characteristics of a person, and gender refers to social expectations about the person's characteristics and behavior according to their assigned sex/gender (expected masculine or feminine traits). Gender identity is defined as a person's internal psychological identification, which may or may not correspond to a person's body or assigned sex. Transgender people are an example of people whose gender identities does not correspond to their assigned sex, i.e. whose gender is outside the scope of traditional, socially defined gender roles and norms. Despite greater recognition of people with non-binary gender identities today, many social structures are still very much marked by the gender binary. Therefore, people whose gender identity or expression does not fit into the gender binary are exposed to stereotypes, stigmatization, transphobia, cisgenderism, and unfavorable treatment. Croatian society, which is the social context of this research, is characterized by ambivalent influences on the position of transgender people. Croatia is one of the European Union member states with the most traditional gender norms. Due to the greater visibility of gender nonnormative people, more anti-gender movements have appeared recently. Also, transgender people in Croatia are still often exposed to discriminatory and violent treatment in society. At the same time, the activism of LGBTIQ+ people has significantly contributed to the improvement of social attitudes about transgender people and legal protection. Transgender people in Croatia are protected by anti-discrimination laws and have the possibility of accessing gender affirmation and legal gender recognition. The theoretical framework of this research is the gender minority stress model by Hendricks and Testa, which is an adaptation of Meyer's minority stress model. The gender minority stress model describes the distal and proximal stressors to which, in addition to common life stressors, transgender and gender non-conforming people are exposed. Distal or external stressors include experiences such as gender-related violence, gender-related discrimination, gender-related rejection and nonaffirmation of gender identity. The second category of minority stressors, proximal or internal stressors, are internalized transphobia, concealment of identity and negative expectations (fear of further victimization or discrimination). Because of this accumulated stress, transgender and gender non-conforming people are at increased risk of impaired mental health and well-being. The model also lists stress-relieving factors such as pride in identity, social support, and connectedness with transgender community. What sets this research apart from others in the field of gender minority stress is its focus on positive mental health (flourishing), rather than solely on mental health problems. Previous research in Croatia has investigated certain dimensions of gender minority stress, but none of the studies has covered all dimensions of this model. Also, the focus was mainly on people who approached the gender adjustment process, so those transgender people who did not affirm gender were omitted. Because of that, it is justified to focus on transgender people, regardless of whether they have affirmed gender, as well as on aspects of gender minority stress in the Croatian context that have not been covered so far. Research aim and research questions This research aimed to deepen the understanding of the model of gender minority stress in the Croatian context, starting from the experiences of transgender people. Therefore, the research aim was to describe distal and proximal stressors of transgender people living in the Republic of Croatia, their coping mechanisms, and their perception of their mental health. The stated goal was operationalized through the following research questions: 1) What distal and proximal stressors are described by transgender people living in the Republic of Croatia? How do the described stressors fit into the gender minority stress model? 2) What coping mechanisms do transgender people living in the Republic of Croatia use? How do these coping mechanisms fit into the gender minority stress model? 3) How do transgender people living in the Republic of Croatia perceive their mental health? Methodology A qualitative research approach was used following the research aim and questions. Purposive sampling and the snowball method were chosen for the recruitment of participants. They were reached by contacting NGOs, via Instagram, and through acquaintances of the researcher. Participants are mostly transgender men and those who affirmed their gender to some extent. They are also mostly younger, Croatian, single, highly educated / currently in the higher education system, and living in urban areas. The self-assessment of the socioeconomic status of most participants is average or slightly better than average. 20 semi-structured interviews (face-to-face or online) were conducted in September and October of 2022. After the interview, the participants completed the sociodemographic characteristics questionnaire and the Croatian version of the Mental Health Continuum-Short Form. The collected data were processed using the process of inductive thematic analysis. Coding of data was carried out through the MAXQDA program. The quantitative data were analyzed using methods of descriptive statistics within the SPSS program. Before the start of the data collection, the approval of the Ethics Committee of the Faculty of Law in Zagreb was obtained. During the data collection and analysis, the principles of respecting autonomy, well-being and non-harm were applied. Participants were informed of all ethical aspects through the Participant Notice before consenting to participate (by signing informed consent). Multiple strategies for ensuring the reliability of research, in terms of dimensions of credibility, transferability, auditability, and confirmability, were applied during the design and implementation of the research. Results The research results are consistent with the theoretical model of gender minority stress, which was the theoretical starting point of this research. They show that transgender people in Croatia experience multiple distal stressors, at the structural, institutional, and interpersonal levels. The most common experiences include nonaffirmation of gender identity, gender-related unsupportive reactions, gender-related discrimination, and gender-related victimization, with gender-related victimization being least present. Interpersonal minority stressors have been experienced in environments such as the family, the wider environment, and public institutions (primarily healthcare and education system). Due to distal stressors, internalization of negative attitudes about transgenderism, gender concealment, and negative expectations are present as proximal stressors. Transgender people in Croatia use different coping mechanisms at the individual and group levels, some of which are adaptive and some are maladaptive. As the most important coping mechanisms, participants recognized gender affirmation, inclusion in the trans community, and social support, and it can be assumed that some participants developed resilience to minority stressors. Participants vary according to their perceived mental health, noticing the contribution of minority stressors to impaired well-being. The highest values are present on the dimension of psychological well-being, and the lowest on the dimension of social well-being. Seven participants have high mental health, eleven of them have moderate mental health, and one participant has low mental health, meaning only a third are flourishing. It can be concluded that minority stress affects the mental health outcomes of transgender people in Croatia, although some of them have developed resilience to minority stress. Given all of the above, a conclusion can be drawn that the model of gender minority stress applies to the Croatian context. Conclusion The results indicated the presence of distal and proximal stressors in the Croatian transgender population. In addition, transgender people in Croatia use multiple coping mechanisms, the most significant of which are gender affirmation and pride, inclusion in the transgender community, and social support. One can see the contribution of minority stressors, as well as resilience, to mental health outcomes. A third of the participants have high mental health, most participants (eleven) have moderate mental health, and one participant has low mental health. In other words, approximately a third of the participants flourish. The estimated scientific contribution of the doctoral dissertation is the verification and deeper understanding of the model of gender minority stress in the Croatian context, the description of distal and proximal stressors, coping mechanisms, and mental health from the perspective of transgender people. The recommendation for future research is to further deepen the results of this research and to focus on subgroups underrepresented in this research (such as trans women, trans older people, and those from rural areas), as well as people with intersectional identities. Also, research in general needs to be more inclusive in terms of people of minority gender identities. Recommendations for experts and general public include increasing knowledge and sensitizing the public and experts on trans topics, adaptation of existing services to people with minority gender identities, providing support to trans people and their family members, and interventions aimed at encouraging protective factors or increasing positive mental health.