The present study aimed to investigate whether the strength of mental health competencies and the severity of mental disorder symptoms, and their interaction, differ in the strength of their associations with several dimensions of well-being in Hungarian adult psychiatric and non-clinical samples. All respondent in the psychiatric sample (129 patients (44 male, 85 female)) and in the non-clinical community sample (253 adults (43 male, 210 female)) completed the Mental Health Test, six measures of well-being and mental health, and the Symptom Checklist-90-Revised. Including both mental health competencies and mental disorder symptoms in a regression model in both samples can predict patients’ well-being even more accurately. Mental health competencies were positively related; mental disorder symptoms were negatively related to subjective well-being. In all models and in both samples, mental health competencies were found to be stronger determinants of well-being than mental disorder symptoms. The interaction of mental health competencies and mental disorder symptoms is no more predictive of well-being in either psychiatric or non-clinical samples than when the effects of each are considered separately. The assessment of mental health competencies has an important predictive value for well-being in the presence of psychopathological symptoms and/or mental disorders.