Abstract
This Special Series addresses categorical and dimensional models of assessment and diagnosis in evaluating patients with personality disorders (PDs). Although the categorical-dimensional debate has been around for some time, there has been increased interest in this topic recently. For example, the April and June 2005 issues of the Journal of Personality Disorders (Volume 19, Numbers 2 and 3) were devoted exclusively to discussion of a research agenda for developing a dimensional classification system for PDs. Papers were taken from a conference held at American Psychiatric Association headquarters in December 2004 on the topic of PD classification for the Diagnostic and Statistical Manual of Mental Disorders (4th ed. [DSM—V]; CitationAmerican Psychiatric Association, 1994). As Widiger and Simonsen (2005) noted in their introductory article, although a dimensional classification system may not be present in the next edition of the DSM, “it is hoped that the publication of these articles will indeed provide further support for and stimulation toward the eventual adoption of a dimensional model of personality disorder by the APA [American Psychiatric Association] and WHO [World Health Organization]” (p. 106). Contributors to this Special Series note various issues inherent in the paradigmatic shift described by CitationWidiger and Simonsen (2005) and discuss topics relevant to the transition to a dimensional model of PD assessment. An emerging theme in this series is that the move toward a dimensional model—although desirable—presents several challenges that must be addressed if such a change is pursued. Continued attention to these issues may help circumvent problems that might otherwise occur as researchers and clinicians implement this change. It is our hope that a consideration of these challenges and their implications will allow the field to evolve in such a way that more integrated, valid, and useful models of PDs and their assessment emerge.