 Borderline personality disorder BPD is a serious and debilitating psychiatric condition characterized by instability in relationships, emotions, identity, and behaviour. Affecting 2-6 of the general population, BPD is associated with high rates of self-harm both suicide attempts and non-suicidal self-injury, mortality by suicide, and consequent heavy use of public health resources, making it one of the most expensive psychiatric disorders to treat. Psychotherapy is recognized as the first-line treatment for BPD, of which dialectical behaviour therapy DBT has demonstrated the strongest empirical support. Although DBT is efficacious for self-harming individuals with BPD, and increasingly available over the past 10 years, demand for DBT exceeds existing resources. 