Introduction: In adolescents, difficulties with emotional regulation and self-harming behavior are on the rise. One of the most effective treatments for this population is Dialectical Behavior Therapy for Adolescents (DBT-A). While clinical trials have demonstrated the efficacy of DBT-A, there is limited research on its effectiveness in real-world settings. Aim: This study aims to fill that gap by reporting on treatment outcomes from a naturalistic study, focusing on the response trajectories of adolescents undergoing a 20-week DBT treatment. Methods: Ninety-six adolescents aged 13 to 18 participated in DBT-A treatment. We assessed DSM-V axis diagnoses, depressive and borderline symptoms, emotion regulation difficulties, coping mechanisms, self-injury, suicidal ideation, and suicide attempts at baseline and post-treatment. Using latent class analysis (LCA), we identified potential response trajectories based on the frequency of deliberate self-harm (DSH) and emotion dysregulation (ED) as indicator variables. Results: Three distinct classes emerged, illustrating different response trajectories regarding DSH. Class 1 showed no DSH episodes at baseline or post-treatment. Class 2 exhibited frequent DSH episodes at baseline, which decreased to a low level by the end of treatment. Class 3 had frequent DSH at baseline, which decreased but remained relatively high at the end of treatment. Similar trajectories were observed for ED. Favorable trajectories were associated with lower levels of borderline symptoms at baseline. Conlusions: These findings highlight identifiable patterns in treatment response and indicate significant recovery for most participants post-treatment. This suggests the potential effectiveness of DBT-A in addressing emotional regulation and self-harming behaviors in adolescents.