BACKGROUND: Emotion regulation difficulties have been identified as an underlying mechanism in the development and maintenance of psychopathology. The need to improve our understanding of emotion regulation difficulties to accurately assess and treat adolescents in child and adolescent psychiatric settings is essential. METHOD: In the first part of the study, the psychometric qualities of the Difficulties in Emotion Regulation Scale, 16-item version (DERS-16) were examined in a clinical child and adolescent psychiatric (CAP) sample. In the second part, the DERS-16 was used to examine emotion regulation difficulties in the CAP sample (N = 281, 15-19-year-olds, 77.6% female) and in a community sample of adolescents (N = 3,169, 16-19-year-olds, 55.6% female). Subgroups were further explored in the CAP sample by two-step cluster analysis with log-likelihood distance measures. RESULTS: DERS-16 showed satisfactory psychometric qualities in the CAP sample. DERS-16 successfully distinguished adolescents in the clinical sample from adolescents in the community sample. Results showed significantly higher levels of self-reported emotion regulation difficulties in the CAP sample and in females. The two-step cluster analysis resulted in three clusters, named Minor, Moderate and Severe emotion regulation difficulties. Adolescents with the highest levels of emotion regulation difficulties had significantly more risk behaviors such as nonsuicidal self-injury and drug use, depression and anxiety, exposure to abuse, and higher levels of comorbidity. CONCLUSIONS: DERS-16 successfully distinguished clinical from community adolescents. The results illustrate the importance of identifying adolescents with high levels of emotion regulation difficulties in child and adolescent psychiatry due to higher levels of comorbidity and risk behaviors.