•This study gives the preliminary feasibility, acceptability, and efficacy of two iterative case series using outpatient DBT for adults with AN. Case series one had a low patient dropout rate of 16% and a modest effect size increase in BMI of d= -0.50.

•Case series two showed the effectiveness of an augmented DBT program for patients with AN focusing on overcontrolled emotions and behaviors, as evidenced by the low treatment dropout rate of 11%. The patients also rated the treatment highly in regards to its suitability and confidence they would have recommending the treatment to others. Case Series 2 resulted in effect sizes for BMI of d= -1.12 from baseline to post-treatment, that were sustained at 6 months (d= -0.87) and 12 months follow-ups (d= -0.21).

•In summary, this study provided evidence of the effectiveness of both standard and augmented DBT on treating AN, showing that a DBT program focused on overcontrolled emotions and behaviors may be helpful in encouraging long term results.