Sleep-disordered breathing (SDB) in children is associated with poor school performance, with minority children being at increased risk for both conditions. The latter have been attributable to low socio-economic status (SES). To further study these relationships, the contribution of SES to SDB and learning was examined in 1,010 validated questionnaires collected from parents of both white and African-American low-SES preschoolers. Twenty-two percent of disadvantaged preschoolers were reported to be at risk for SDB. These children were more likely to be African American, and had a higher incidence of daytime sleepiness, lower academic performance, and hyperactivity. Maternal education level did not account for these differences.