Although we sympathize with the wish to examine the effectiveness of different psychotherapy systems for patients with personality disorder, there is a clear limitation of lumping together studies looking at the efficacy of treatment for so many different kinds of patients. It could be that instead of having found support for the dodo bird verdict (psychotherapeutic equivalence), these studies could show that different therapies are better at helping patients with different personality disorders. Therefore, the lack of apparent differences between treatments might, for example, be due to the possibility that cognitive therapies are more effective with patients with avoidant personality disorder, while interpersonal/dynamic therapies might be more effective with obsessive-compulsive personality disorder.