Substance use comorbidity in psychotic disorders has been described as “the rule rather than the exception”, and is often deleterious to the clinical course of illness. Cannabis (marijuana) is one of the most commonly used substances by patients with schizophrenia and related psychotic disorders. Modulation of the endocannabinoid system by the main psychoactive component in marijuana, Δ9-tetrahydrocannabinol, can induce acute psychosis and cognitive impairment. Over the past two decades, there has been extensive research on the association between cannabis and psychosis. The purpose of this presentation is to synthesize recent research in this area, including associations between cannabis and psychosis risk; the epidemiology and phenomenology of psychosis and comorbid cannabis use; and associations between cannabis use and clinical course, and outcomes in psychosis.