The authors review recent studies that assess the impact of personality pathology on the treatment outcomes of axis I disorders. Studies reported include both structured treatment trials and surveys of the outcome of naturalistic treatment. Personality diagnosis in each of the studies reviewed was established by a structured diagnostic instrument. In some of the studies examined, personality traits, not categorical personality diagnoses, are reported in relation to treatment outcome. The authors describe 17 studies published within the past 3 years, and discuss them in relation to a previous review that covered 21 earlier studies. Consistent with previous investigations, recent studies continue to describe an adverse impact of personality pathology on the treatment outcome of a wide range of axis I disorders. The authors examine new studies that describe the effect of specific aspects of personality dysfunction on outcome measures of axis I disorders. New developments in this area include the predictive importance of both personality traits and disorders as well as possible specificity of traits in predicting outcome in some circumstances.