Summary The efficacy of psychological interventions for the treatment of addiction problems has received considerable attention in the research literature as well as within the policy and service arenas. Psychological interventions can be used on their own or as an adjunct to pharmacological treatments. In UK drug treatment services attempts have been made to disseminate interventions based on psychological models of understanding addictive behaviours. There is an encouraging evidence base for the effectiveness of psychological interventions for a wide variety of addictive behaviours. Evidence-based psychological treatments include cognitive–behavioural and motivational treatments, contingency management, 12-step approaches and family and social interventions. Although the literature suggests that such treatments lead to improved outcomes when compared with no treatment at all, the evidence favouring one type of psychological intervention over another is less clear. Further research comparing the effectiveness of a broad range of psychological interventions delivered as brief or longer-term treatments needs to be undertaken with particular emphasis on pragmatic trials delivered in routine clinical settings and cost-effectiveness analyses. Other factors such as therapist characteristics and service variables are important in determining treatment effectiveness and need to be the focus of further research studies.