Substance abuse seems to be common among those with early signs of evolving psychosis. This article seeks to determine the prevalence of substance abuse and substance use disorders (SUDs) and the association of abuse and SUD with vulnerability psychosis among a sample of first-degree relatives of schizophrenic patients (n = 70), help-seekers (n = 29), and control subjects (n = 34). The Structured Interview for Prodromal Symptoms (SIPS) 1.0 was used to define the vulnerability status and the Structured Clinical Interview for DSM-IV Axis I to diagnose the subjects. Data on various other measures, including premorbid adjustment, personality disorder symptoms, psychological distress, and abuse of substances, were collected. Those who were identified as vulnerable to psychosis reported significantly more lifetime alcohol abuse and had more commonly an SUD than controls. Substance use disorder, as well as alcohol and drug abuse, correlated significantly with personality disorder symptoms and current positive SIPS score and both types of abuse also with disorganization SIPS score. The odds ratio for having an SUD among those vulnerable to psychosis was 6.33 (95% confidence interval, 1.77-22.73). Early psychosis and substance abuse frequently occur together.