Adolescent cannabis use has been shown to increase risk of later psychosis and childhood trauma is associated with both substance misuse and risk for psychosis. Psychotic symptoms in adolescents have been linked with later common mental disorders as well as psychotic outcomes, however personality disorders have not been investigated. There is limited information on rates of psychiatric disorder among adolescents and adults with psychotic symptoms in community samples, and no information on rates of personality disorders in this group. This study aimed to investigate prevalence (in adolescence and young adulthood), incidence and persistence rates of psychotic symptoms in a young Irish population, and whether early versus later onset of cannabis use and childhood trauma increase risk of psychotic symptoms, separately and/or by an interaction effect. Adult psychiatric outcomes and comorbidities of psychotic symptoms were also investigated.