Structured instruments for the global assessment of personality disorder are rarely used in clinical assessments, possibly due to their limited validity and clinical utility. The Shedler-Westen Assessment Procedure-200 (SWAP-200) was developed to address these limitations. This paper reports on the testing of 30 subjects from a high-security hospital in the United Kingdom. The testing was done with the SWAP-200, the Structured Clinical Interview of DSM-IV Personality Disorders (SCID-II), the Adult Attachment Interview (AAI), and the Chart of Interpersonal Reactions in Closed Living Environments (CIRCLE). Eighty percent of the sample had previous convictions and had served up to 16.4 years in prison. This study's preliminary results indicate the reliability and validity of the SWAP-200 in a personality-disordered forensic population. Of particular importance are the findings that the SWAP-200 decreased the frequency of diagnostic overlap of personality disorder categories compared with the SCID-II and showed more significant associations with other instruments that measure or relate to interpersonal functioning. The findings suggest that the SWAP-200 can be used to structure clinical diagnosis and that it is the diagnostic procedure rather than the use of data collected from structured self-report interviews that improve the diagnosis of personality disorder. Further, the preliminary finding of a decreased frequency of diagnostic comorbidity of personality disorder opens the possibility of further assessing the contribution of personality factors in treatment and risk-management planning. 6 tables and 42 references