Background Aggression and violence are serious problems in schizophrenia. Cognitive-behavioural therapy (CBT) has been shown to be an effective treatment for psychosis although there have been no studies to date evaluating the impact of CBT for people with psychosis and a history of violence.Aims To investigate the effectiveness of CBT on violence, anger, psychosis and risk outcomes with people who had a diagnosis of schizophrenia and a history of violence. Method This was a single-blind randomised controlled trial of CBT v. social activity therapy (SAT) with a primary outcome of violence and secondary outcomes of anger, symptoms, functioning and risk. Outcomes were evaluated by maskedassessors at 6 and 12 months (trial registration: NRR NO50087441). Results Significant benefits were shown for CBT compared with control over the intervention and follow-up period on violence, delusions and risk management. Conclusions Cognitive-behavioural therapy targeted at psychosis and anger may be an effective treatment for reducing the occurrence of violence and further investigation of its benefits is warranted.