["Child and Adolescent Mental Health, EarlyView. ", "\n\nBackground\nAdolescence is a period marked by critical developmental milestones, during which many mental health issues, including internalizing disorders, often first emerge.\nThese disorders can significantly impair socialization, a key process for developing identity, social skills, and supportive relationships. Mentalization has gained attention as a crucial factor in effective socialization. While mentalization deficits have been widely studied in adults with mental health issues, evidence of this association in adolescents remains limited.\n\n\nMethods\nFollowing PRISMA reporting guidelines, we performed a systematic search and multilevel meta‐analysis of studies examining the association between mentalization and mental health indicators in adolescents with internalizing disorders. Records were screened independently by two reviewers, with additional studies identified via reference‐list checks. Studies were included if they assessed mentalization and internalizing‐related mental health outcomes in adolescents and provided correlational data. Methodological quality was appraised using a tailored 7‐domain checklist. Correlational multilevel meta‐analyses were conducted using Fisher's z transformation and a three‐level random‐effects model to address variability at within‐effect size, between‐effect size, and between‐study levels.\n\n\nResults\nThe final sample included 23 studies (reporting 154 effect sizes) that met inclusion criteria. Included studies showed overall moderate‐to‐low risk of bias. The models showed a significant, medium‐sized negative correlation between mentalization and mental health indicators (z = −0.24, p < .001, r = −0.24). Sensitivity analyses found no significant effect of the moderators.\n\n\nConclusion\nThis is the first meta‐analytic study to estimate the association between mentalization and mental health outcomes in adolescents with internalizing disorders. Findings suggest a moderate association, underscoring the importance of assessing mentalization in these populations. Further research should explore the clinical implications of mentalization for internalizing disorders in adolescence.\n\n"]