The second study of the cluster (‘Cognitive-behavioural treatment for adolescents with PTSD and SUD’; PI: Rainer Thomasius, Hamburg) examines the feasibility and efficacy of the adolescent version of SS in N = 74 adolescent girls diagnosed with PTSD related to CAN and substance use disorders. As in the first study of the cluster, the decision to focus on girls was made because of the higher prevalence of the comorbidity of SUD and PTSD in females, and the advantages related to offering trauma treatment in gender-specific groups. In this uncontrolled pilot study, it is expected that participants attending at least eight of 14 SS sessions (‘completers’) will show a significant reduction of posttraumatic symptoms at three-month follow-up as compared to baseline, as well as significant reductions of substance use.