It is well established that a high proportion of help-seeking substance users have at least one personality disorder (PD) (Verheul, 2001). In a recent national survey on alcohol use and related conditions in the general population in the United States (Grant, Stinson, Dawson, Chou, Ruan, & Pickering, 2004), among individuals with a current alcohol use disorder, 28.6% had at least one Diagnostic and Statistical Manual of Mental Disorders (4th ed.) (DSM-IV) PD. Among those with a current drug use disorder, this was the case in 47.7%. Antisocial (ASPD), obsessive-compulsive, and paranoid PDs were the most prevalent in both subgroups. Both alcohol-and drug-use disorders were most strongly related to antisocial, histrionic, and dependent PD in the general population. In a U.S. sample of patients referred for treatment of PDs, 60% of the patients with substanceuse disorders (SUD) had a PD, with borderline PD (BPD) and ASPD being most strongly associated with the use of nonalcoholic, noncannabinoid drugs (Skodol, Oldham, & Gallaher, 1999). In a Dutch sample of 370 treated substance users, Verheul, Kranzler, Poling, Tennen, Ball, and Rounsaville (2000) found that 57% had at least one DSM-III PD, with the paranoid subtype the most prevalent among cluster A disorders, BPD among cluster B, and avoidant among cluster C disorders. The strongest associations between PD and Axis I disorders were between social phobia and avoidant and schizotypal PD, and between major depression and BPD. In a Norwegian consecutive sample of treated substance users from two catchment areas (Landheim, Bakken, & Vaglum, 2003), 72% had one or more PD, with the incidence reaching 79% among polysubstance users and 66% among pure alcoholics. Polysubstance users significantly more often had cluster B disorders (58% vs. 27%), and pure alcoholics more often had cluster A disorders (44% vs. 31%) and cluster C disorders (28% vs. 11%).