Although comorbid substance use is a common problem in bipolar disorder, there has been little research into options for psychological therapy. Studies to date have concentrated on purely cognitive behavioural approaches, which are not equipped to deal with the ambivalence to change exhibited by many towards therapy designed to change substance use. This paper provides the first report of an integrated psychological treatment approach for bipolar disorder with comorbid substance use. The intervention reported combines motivational interviewing and cognitive-behavioural therapy to address ambivalence and equips individuals with strategies to address substance use. Across five individual case studies, preliminary evidence is reported to support the acceptability and the feasibility of this approach. Despite most participants not highlighting their substance use as a primary therapy target, all but one exhibited reduced use of drugs or alcohol at the end of therapy, sustained at 6 months' follow-up. There was some evidence for improvements in mood symptoms and impulsiveness, but this was less clear-cut. The impact of social and relationship issues on therapy process and outcome is discussed. The implications of the current findings for future intervention research in this area are considered. Copyright (C) 2011 John Wiley & Sons, Ltd.