An investigation was made of the language of three mothers to their infants between the ages of two months and eight months in order to chronicle pragmatic changes in the mothers' language as the infants progressed from Piaget's Stage 2 (primary circular reactions) to Stage 3 (secondary circular reactions) of sensorimotor development.Results indicated that the mothers modified their speech to their infants when the babies began to display primarily Stage 3 behaviors. That is, a greater proportion of their speech referred to the child interacting with objects, while their references to the child alone decreased. They used a greater proportion of meaningful utterances and more reference in their speech. A decrease in the use of language to maintain interaction with the infant and an increase in its use to regulate the child's behavior or teach the child was noticed. Finally, the mothers used less repetition as their infants entered Stage 3. These language modifications would not be apparent in an analysis limited to syntactic or semantic aspects.