Skin conditions can be associated with heightened levels of psychological morbidity, suggesting the need for psychological interventions. A number of specific interventions (such as habit reversal) have been developed. However, to date, there has not been a systematic review of the effectiveness of psychological interventions. We sought to systematically evaluate the effectiveness of psychological interventions designed to improve the severity of and adjustment to skin conditions in adults. Database, archival and citation searches were conducted. Studies were included if participants were allocated to either a psychological intervention (excluding educational interventions and complementary therapies) or a comparison condition, and if they measured outcomes relevant to the skin condition. Twenty-two studies met these inclusion criteria. Effect sizes for each intervention were computed and we also coded a number of potential moderators of intervention efficacy. Psychological interventions were found to have a medium-sized effect on skin conditions (g = 0·54). The type of skin condition, age of sample, nature of the intervention, time interval between the end of the intervention and follow-up, and type of outcome measure all moderated the effect of interventions on outcomes. For example, interventions had a medium effect on the severity of the condition (g = 0·40) and psychosocial outcomes (g = 0·53), and a medium-to-large effect on itch/scratch reactions (g = 0·67). Psychological interventions are beneficial for people with skin conditions. However, more research is needed to extend the variety and focus of the psychological interventions that are available. Studies are also needed to explore the longer-term benefits of such interventions.