BackgroundA number of studies in a range of samples attest a link between childhood sexual abuse and psychosis.AimsTo use data from a large representative general population sample (Adult Psychiatric Morbidity Survey 2007) to test hypotheses that childhood sexual abuse is linked to psychosis, and that the relationship is consistent with mediation by revictimisation experiences, heavy cannabis use, anxiety and depression.MethodThe prevalence of psychosis was established operationally in a representative cross-sectional survey of the adult household population of England (n = 7353). Using computer-assisted self-interview, a history of various forms of sexual abuse was established, along with the date of first abuse.ResultsSexual abuse before the age of 16 was strongly associated with psychosis, particularly if it involved non-consensual sexual intercourse (odds ratio (OR) = 10.14, 95% CI 4.8–21.3, population attributable risk fraction 14%). There was evidence of partial mediation by anxiety and depression, but not by heavy cannabis use nor revictimisation in adulthood.ConclusionsThe association between childhood sexual abuse and psychosis was large, and may be causal. These results have important implications for the nature and aetiology of psychosis, for its treatment and for primary prevention.