It is important to recognize that patients who meet DSM-IV-TR diagnostic criteria for BPD are not a single homogeneous group. The polythetic system defines the diagnostic threshold for BPD as any five of the nine criteria for BPD, which results in 256 different combinations of criteria that meet the diagnostic threshold. It is no surprise, then, that treatment studies do not support a "one size fits all" pattern. When colleagues ask me questions such as "Are you a Kernbergian, a Kohutian, or a Fonagian?" I generally reply by saying "that's the wrong question—you first need to describe the borderline patient you have in mind, and then we'll think about which treatment approach might be best for that patient." Even then, it seems probable that a given patient might benefit from more than one type of psychotherapy, and many variables determine the type of therapy selected, such as patient preference, therapist preference (or special training), therapist availability, and the limits of insurance coverage. Plakun et al. (3) described a "Y" model of psychotherapy, emphasizing that many therapies have common core features (the stem of the "Y") such as negotiating and maintaining a therapeutic alliance, and specific treatments have specialized features (the branches of the "Y"), such as a psychodynamic focus or a cognitive behavior focus (3).