30 working-class and 33 upper-middle-class mothers were videotaped in dyadic interaction with their 18-29-month-old children in 4 settings--mealtime, dressing, book reading, and toy play. Samples of the mothers' adult-directed speech also were collected. There were significant social class differences in the mothers' child-directed speech and some parallel social class differences in the mothers' adult-directed speech. These findings suggested that some social class differences in child-directed speech may be instances of more general class differences in language use. There also were main effects of communicative setting on mothers' child-directed speech and interaction effects in which setting moderated the size of the class differences in maternal speech. These findings suggested that the amount of time mothers spend interacting with their children in different contexts may be at least as important an influence on children's linguistic experience as are average characteristics of their mothers' speech.