Background: Three out of ten children in Germany have an immigrant background and this proportion will increase further. While immigrant youth has been found more vulnerable to developing symptoms of depression and anxiety, the underlying mechanisms of how such disparities develop across youth development are still understudied. Some previous research has found that immigrant youth are at risk of experiencing a less positive self-concept compared to non-immigrant youth. We investigated whether the self-concept is a mediator for such mental health disparities. Moreover, we explored variability in such associations from middle childhood to late adolescence.Methods: Overall 1907 children and adolescents aged 5-18 years (M=14 years, SD=3.03, 49.8% female, n=782 with immigrant status) participated in a cross-sectional self-report survey in school settings using scales from the Beck’s Youth Inventories II [1] to assess self-concept and symptoms of depression and anxiety. Links between the immigrant status, age, self-concept and symptom levels of depression as well as anxiety were examined in univariate regression models and moderated mediation models.Results: Immigrant youth reported higher symptom levels of depression and anxiety than their non-immigrant counterparts but did not differ in their self-concepts. Across age groups, self-concept was a significant predictor for symptom levels of depression as well as anxiety, with stronger associations in adolescents. However, the overall hypothesized moderated mediation models were not supported as self-concept neither mediated the link between immigrant status and depression nor anxiety.Conclusions: Our study substantiates previous findings that immigrant youth have increased levels of mental health problems compared to non-immigrant youth. However, our findings also show that immigrant youth do not have a more negative self-concept. The self-concept moreover does not seem to represent a mediator for internalizing mental health disparities. Findings from our study hence suggest that psychosocial interventions for immigrant youth do not require a specific emphasis on self-concept-related components. As our evidence suggests age-moderation of the self-concept on depression and anxiety, psychosocial interventions should consider developing a positive attitude towards the self especially for adolescents. Further research is needed to deepen the understanding of the mediating processes between migration status and mental health variables.