Using the Millon Clinical Multiaxial Inventory ¿ III (MCMI-III), this study examined what personality factors, if any, would predict retention within therapeutic community (TC) treatment for residents presenting with amphetamine-type stimulant (ATS) use disorders. The study utilised a prospective, cohort design. Participants were 213 residents (130 males) from 12 TCs in Australia, with ages ranging from 19 to 58 years. The MCMI-III was administered at the commencement of the study and follow-up discharge information was obtained from TCs at 12 months post-baseline to determine which residents had completed the treatment programme and the reason for discharge. The study revealed a high prevalence of personality and psychopathology symptomatology within an ATS-using population with scores in the clinical range (>84) on a number of personality factors. Those most likely to have left treatment prematurely or been discharged scored higher on Antisocial, Narcissistic, Negativistic, Sadistic, Schizoid, Schizotypal, Alcohol Dependence, Drug Dependence, Dysthymia, and Major Depression scales. However, no significant personality differences were observed between programme completers and non-completers. While a follow-up measure of personality was not taken, results of this study suggest personality functioning may be improved during treatment. This raises possibilities for TCs and other treatment services in relation to the inclusion of specific treatment interventions within the TC. It is recommended that future research examine the extent to which ATS users' personality pathology changes during TC-based treatment, to provide a further insight into suitable evidence-based treatment approaches specific to an ATS-using population.