The speech that upper-middle class mothers used with their young children was compared to that used by working class mothers. Mother-child interaction was recorded in four settings: mealtime, dressing, reading, and playing with toys. Also investigated were mothers' child rearing beliefs and goals. Participants included 33 upper-middle class and 30 working class mother-child dyads. Children were selected to be comparable in level of productive language use. In terms of Roger Brown's stages, all were Stage I speakers. Findings indicated that the working class mothers talked less to their children than did the upper-middle class mothers, and when they talked their speech differed in its functional, discourse, and lexico-syntactic properties. Upper-middle class mothers talked more per unit of time and sustained longer interactions with children. Effects and non-effects of setting support the contention that the press of external factors does not explain observed class differences in the mothers' speech. Differences in beliefs, attitudes, and goals described by mothers were few and without explanatory force. Analyses of the language mothers used in response to interview questions suggested that mothers talk differently to their children because they talk differently to everybody. Concluding remarks speculate on the consequences of class differences in maternal speech. (RH)