In this master's thesis, the Adult Attachment Projective Picture System (AAP) was used as an add-on treatment tool in a short-term attachment-specific intervention in inpatient adolescents, with the study by Finn (2011) as the main frame of reference. In order to examine the added value of the AAP as an additional treatment tool for the usual inpatient setting (TAU), the data of one patient from the index group and one patient from the control group were used as an example. It was expected that some aspects of the attachment representation of the index patient would change. In both groups, the AAP, the SCL-90®-S, the BDI-II, the CTQ-SF and the YSR / 11- 18R were conducted at the beginning (T1) and at the end (T2) of the hospitalization in the child and adolescent psychiatry. The index group received the attachment-specific intervention, which consisted of working through the AAP narrative. Both patients showed a general improvement in symptoms. However, the change in the insecure attachment representation classified at T1 in both patients to a secure attachment representation was identified at T2 only in the index patient. In addition, the therapist behavior in the attachment-specific interventions of the entire sample was qualitatively evaluated on the basis of deductively derived categories, in terms of a future manualisation of AAP. The evidence-based model Secure Cycle by Kobak et al. (2015) was applied for the creation of the categories. The four theory-based categories of Kobak and colleagues (2015) have been successfully used to (AAP- specifically) define the therapist behavior. Another category was additionally developed. Afterwards the theoretical and practical implications of the gained implications are discussed and impulses for further research are derived.