An increasing volume of evidence suggests that mentalization (MZ) can be an important factor in the transition from mental health to mental illness and vice versa. However, most studies are focused on the role of MZ in specific disorders. This study aims to evaluate the relationship between MZ and mental health as a trans-diagnostic process. A sample of 172 adolescents aged 12 to 18 years old (M = 14.6, SD = 1.7; 56.4% of girls) was assessed on measures of MZ, psychopathology and psychological functioning from a multimethod and multi-informant perspective. Contrary to predictions, MZ was not associated with general psychopathology and comorbidity, even when explored from a broad, trans-diagnostic perspective. However, we observed a robust association linking MZ to functioning and well-being across many dimensions, involving social, role and several psychological indicators of adjustment and mental health. These results suggest that MZ may contribute to mental health beyond symptoms, not so much associated with psychopathology, but rather resilience and well-being.