The Wisconsin Personality Disorders Inventory (WISPI-IV; Klein & Benjamin, 1996) is the latest version of a self-report measure of DSM-IV personality disorders (PDs) derived from an interpersonal perspective. When categorical diagnoses derived from the WISPI-IV were compared with independent SCID-II diagnoses, the majority of the kappas were poor (>.40). However, all but one of the effect sizes for the differences in WISPI-IV means between groups with and without SCID-II diagnoses were large (>.80). When SCID-II and WISPI-IV dimensional scores were considered, the average r between profiles was .61 (median = .58) and correlations between corresponding PD scales (mean diagonal r = .48; mean off-diagonal r = .18) indicated good convergent and discriminant validity for five of the WISPI-IV scales. These results add to the cumulating evidence suggesting greater reliability and validity of dimensional over categorical scores for PDs. Researchers and clinicians interested in having an efficient method of assessing PDs may consider using a dimensional approach such as the WISPI-IV as an alternative to diagnostic interview.