Personality disorders are currently conceptualized as “qualitatively distinct clinical syndromes” in the American Psychiatric Association’s (APA) Diagnostic and Statistical Manual of Mental Disorders (DSM-IV; APA, 2000, p. 689). However, researchers have increasingly recognized the limitations of the categorical model (Clark, in press; Krueger, Markon, Patrick, & Iacono, in press; Livesley, 2003; Trull & Durrett, 2005; Watson, in press; Widiger & Samuel, in press). In 1999, the APA and the National Institute of Mental Health (NIMH) organized a series of work groups to develop a research agenda for the forthcoming DSM-V (McQueen, 2000). The Nomenclature Work Group, whose role was to examine the fundamental assumptions of the diagnostic system, concluded that it would be “important that consideration be given to advantages and disadvantages of basing part or all of DSM-V on dimensions rather than categories” (Rounsaville et al., 2002, p. 12). The Nomenclature Work Group further recommended that the personality disorders might be an appropriate initial section to try a dimensional model of classification. “If a dimensional system of personality performs well and is acceptable to clinicians, it might then be appropriate to explore dimensional approaches in other domains” (Rounsaville et al., 2002, p. 13).
The DSM-V white papers are being followed by a series of international conferences whose goal is to further refine the research agenda for DSM-V. The first of these conferences, “Dimensional Models of Personality Disorder: Etiology, Pathology, Phenomenology and Treatment” was held in December of 2004 (First, 2005). The purpose of this conference was to generate a research agenda that would help advance the field toward a dimensional classification of personality disorder. Topics covered included biogenetics,