The most common form of dual diagnosis is personality disorder and substance abuse (Verheul, van den Bosch and Ball, 2005). Antisocial and borderline personality disorders are most prevalent in substance abuse patients, followed by Cluster C (especially avoidant personality disorder) and Cluster A (especially paranoid personality disorder) (Rounsaville et al., 1998). Thus far, remarkably few studies have been carried out into the treatment of these dual diagnosis problems despite the high comorbidity. A proposal is made in this chapter for a schema mode-focused, integrated treatment of Cluster B personality disorders and addiction problems (i.e., substance abuse, drug-dependence, and gambling). The basic principles for this are Young's schema mode models for borderline and narcissistic personality disorders, Bernstein, Arntz and de Vos's (2007) adjusted schema modes for antisocial personality disorders and psychopaths in forensic settings, and evidence-based treatment for addiction, such as motivational interviewing, self-control techniques, social and problem solving skills training, relapse-prevention training, and contingency management (Emmelkanip and Vedel, 2007).