Personality disorders (PDs) are still classified through categorical taxonomies that are at odds with current research findings. Dimensional models provide a suitable alternative for measuring individual differences. However, as they have traditionally lacked a clear definition of the "disorder" construct, the clinical utility of these models has been limited. This study tests whether Cloninger's dimensional model is able to capture two domains: the features that differentiate PD subtypes from each other and the common core features underlying all PDs. Seventy-four drug dependent patients were independently assessed using the SCID-II and Cloninger's TCI. There was a slight relationship between TCI temperament dimensions and the DSM personality disorder subtypes, but the association was not specific enough to allow differential diagnosis, The character dimension Self-Directedness was strongly associated with the presence and severity of all PDs, irrespective of subtype, correctly classifying 77% of subjects. Character dimensions are a reliable, valid and low-cost tool for detecting PDs in drug abusers and may help to provide an operational definition of the common core features underlying all PDs.