Conventional and displaced uses of pronouns in maternal speech to refer to the baby were investigated in a developmental study of six mother—infant dyads using video-recordings of their free play at three, seven and ten months. These pronominal uses were analysed in a number of semantic contexts to determine how interactive situations influence the use of different types of pronouns. Results show that third- and first-person pronouns occur significantly more often in the semantic context of affect-oriented activities than in the semantic context of goal-directed activities. For second-person pronouns the results are the opposite. The contrast found between these two contexts, i.e. where the child is presented as the agent of a meaningful activity or not, shows how the place constructed for the baby as an interlocutor in maternal speech evolves with age. This study underlines the part the third person plays with its descriptive value in the acquisition of the system of pronouns.