Objective: To test the diagnostic constructs implied by DSM-IV Axis-II personality disorders by examining relationships between different combinations of DSM-IV criteria.

Method: Confirmatory factor analysis was used to test the borderline, schizotypal, avoidant and obsessive-compulsive personality disorder constructs in a large treatment-seeking sample (N=668) from a multisite study. A model based on the three DSM-IV Axis II clusters was also tested. Both models were tested against a unitary ‘generic’ model constructed from four criteria sets combined.

Results: Goodness-of-fit for both the three-cluster and four disorder models was significantly better than the unidimensional model, and the four-disorder model was significantly better than the three-cluster model.

Results were replicated using data from 2-year follow-up obtained by interviewers blind to original Axis II diagnoses at baseline.

Conclusion: Support is provided for the DSM-IV disorder-level classification for schizotypal, borderline, avoidant and obsessivecompulsive personality disorders in a treatment-seeking sample.