Prior studies of violence among individuals with mental illnesses have focused almost exclusively on individual-level characteristics. The present analysis focused on neighborhood factors, including poverty, wealth, family structure, employment, racial and ethnic composition, residential stability, and housing stock. The research took place in Pittsburgh, PA. The study used data on 270 individuals who were treated and discharged from an acute psychiatric inpatient facility, the Western Psychiatric Institute and Clinic, between 1992 and 1995, and on tract-level data from the 1990 census. The participants were all short-stay civil admissions who were between ages 18 and 40 years and spoke English. Information came from interviews with the participants and collateral informants specified by the participants and from official records. Results revealed that living in a socially disorganized neighborhood increased the probability of violence among the participants. In addition, self-reported social supports did not mediate this effect. The analysis concluded that social factors affect the course and manifestations of mental illness and its connections to violence. Tables, footnotes, and 51 references (Author abstract modified)