The rates of substance use and abuse are higher among psychotic patients and antisocial individuals than in the general population. In a 10-year longitudinal study, psychosis-prone individuals identified by the Perceptual Aberration (L. J. Chapman, J. P. Chapman, M. L. Raulin, 1976) and Magical Ideation (Per-Mag) scales (M. Eckblad & L. J. Chapman, 1983), and individuals with antisocial traits, identified by the Impulsive Nonconformity (Noncon) scale (L. J. Chapman et al., 1984), exceeded a control group on rates of substance use disorders. As hypothesized, the Per-Mag group demonstrated preferential patterns of substance use similar to those reported for schizophrenic patients. Participants who scored deviantly on both the Per-Mag and Noncon scales were at especially heightened risk for substance use disorders. Psychosis proneness at the initial screening predicted substance abuse at the follow-up evaluation, but substance abuse at the initial interview did not predict later clinical psychosis or psychoticlike experiences.