The main aim of this project is to determine the short and long-term effectiveness of an out-patient treatment for patients with anorexia nervosa. Specifically, we will measure whether TBT-S in addition to treatment as usual (TAU) will be more effective than TAU alone in reducing eating disorder psychopathology. Assessments will be conducted at four timepoints; pre and post TBT-S, and at 3 and 12 months follow-up. Primary outcome measure is eating disorder psychopathology, with the hypothesis that patients receiving TBT-S in addition to TAU will show significantly greater reduction in eating disorder psychopathology from TBT-S treatment admission to 3 month follow-up, compared to controls.