Abstract. Background: Early interpersonal traumatic events, such as childhood maltreatment, increase the risk of developing complex posttraumatic stress symptoms. The biphasic treatment program STAIR-NT (Skills Training for Affective and Interpersonal Regulation with Narrative Therapy), developed specifically for this patient group, combines interventions to improve emotion regulation and interpersonal skills with narrative therapy. Objective: Many affected patients with PTSD after childhood maltreatment also suffer from various comorbid mental disorders and symptoms that can affect and impede the course and outcome of treatment with STAIR-NT. Method: Based on experience from a current treatment study, we provide recommendations for integrating treatment of comorbid mental symptoms into STAIR-NT. Results / Conclusion: Training affective and interpersonal regulation skills in the first treatment phase offers various interventions to efficiently adapt transdiagnostic mechanisms such as emotion dysregulation. In cases of severe comorbid mental disorders or symptoms, adding disorder-specific interventions to STAIR-NT may be indicated.