Diagnosis of comorbid depressive disorder is challenging, even in mental health care. Screening instruments could be economic tools in indicating depression. For the first time, the current study investigates the validity of the newly developed Depression Screener for Teenagers (DesTeen) and its abbreviated five-item form DesTeen-a in a mental health setting.A total of 88 patients aged 13-16 years were recruited in institutions specialized in child and adolescent psychiatry, psychotherapy or psychosomatic medicine. DSM-IV-TR diagnoses of major depression or dysthymia based on a structured diagnostic interview served as the gold standard for validation. For assessing the criterion validity of the DesTeen and the DesTeen-a, areas under the receiver operating characteristic curve (AUC) were calculated. Specificity and sensitivity were computed for optimal cut-off scores according to the Youden Index.Point prevalence of depression was 27.3%. Diagnostic accuracy of the DesTeen was high (AUC=.94). Using a cut-off score of ≥ 18, sensitivity was .96 and specificity was .86. The DesTeen-a showed no loss in validity (AUC=.94). At a cut-off point of ≥ 6, sensitivity remained excellent (.96), while specificity was slightly lower (.80).The limited representativeness and the small sample size restrict the generalizability of the findings.The DesTeen and its abbreviated version are valid instruments to screen for adolescent depression in mental health care. Since structured interviews to diagnose comorbid mental disorders are rarely applied, the DesTeen and the DesTeen-a can support mental health specialists in making the diagnostic process more efficient, thus facilitating effective treatment planning.