Social causation theory and social selection theory have been put forth to explain the finding that low socioeconomic status (SES) is associated with risk for psychiatric disorders. The predictions of both theories were investigated using data from a community-based longitudinal study. Psychosocial interviews were administered to 736 families from 2 counties in New York State in 1975, 1983, 1985-1986, and 1991-1993. Results indicated that (a) low family SES was associated with risk for offspring anxiety, depressive, disruptive, and personality disorders after offspring IQ and parental psychopathology were controlled, and (b) offspring disruptive and substance use disorders were associated with risk for poor educational attainment after offspring IQ and parental psychopathology were controlled. These findings indicate that social causation and social selection processes vary in importance among different categories of psychiatric disorders.