In this pilot study, the effect of a group intervention targeting self-criticism in adolescents in a clinical child- and adolescent psychiatric outpatient setting will be examined using a single-case experimental design (AB). Participants will be randomized to multiple baseline with weekly measures. Our primary outcomes, measured weekly, are self-criticism, nonsuicidal self-injury and symptoms of depression and anxiety, as well as an individually chosen behavior driven by self-criticism. Secondary outcomes are self-compassion, psychological flexibility, quality of life and functioning. In addition to the weekly administered questionnaires, before and after measures, and 3- and 6-month follow-up will be collected. After the treatment, participants will also be interviewed about their experiences of targeting self-criticism.

Inclusion Criteria:

• Patient at the child- and adolescent psychiatric clinic in Linköping, Sweden.
• 15 to 18 years
• an adequate understanding of the Swedish language
• cognitively capable of giving informed consent
• scoring 26 or above on subscale "Inadequate self" and 8.5 or above on subscale "Hated Self" on questionnaire Forms of Self-Criticism and Self-Reassuring Scale (FSCRS)
• the treatment is transdiagnostic so all diagnoses are included (See exclusion criteria for exceptions).

Exclusion Criteria:

• severe anorexia, BMI ≤ 16
• ongoing substance abuse
• diagnosed intellectual disability
• needing interpreter for translation of Swedish language
• participants who cannot give informed consent