This naturalistic study investigated treatment outcomes of Dutch dialectical behaviour therapy for adolescents (DDBT-A) in a sample of 93 adolescents (95.4% female, mean age = 16.20 years) presenting with borderline characteristics, treated at Levvel (a Dutch mental health institution). From baseline to posttreatment significant decreases were found on severity of the borderline symptoms, passive coping style, internalizing and externalizing behavioural problems, and a significant increase on self-worth. Overall, three different therapy formats (outpatient, part-time therapy, and day therapy) showed similar improvements at posttreatment. Concluding, DDBT-A seems promising in reducing borderline related symptoms for adolescents.