Although therapeutic community (TC) treatment is a promising intervention for substance use disorders, a primary obstacle to successful treatment is premature attrition. Because of their prevalence within substance use treatment facilities, personality disorder (PD) diagnoses have been examined as predictors of treatment completion. Prior research on TC outcomes has focused almost exclusively on antisocial personality disorder (ASPD), and the results have been mixed. This study extends previous research by examining the impact of the 10 Axis II PDs on early (first 30 days) attrition as well as overall time to dropout in a 9-month residential TC. Survival analyses indicated that borderline was the only PD negatively related to overall program retention. In contrast, ASPD, as well as histrionic PD, were related to very early attrition, but not to overall program retention. Early assessment and identification of at-risk individuals may improve treatment retention and outcome for TC treatment. (Am J Addict 2011:20:555–562)