This study investigated associations between mother-infant interactions and children's subsequent understanding of mind and emotion. Mothers' tendency to comment on their infants' internal world and their general sensitivity to their infants' internal states were measured through coded play interactions at 10 months. The latter measurement included ratings on four aspects of maternal behaviour: mindful facilitation, joint attention commenting, pacing, and affect catching. In contrast to mothers' internal state language, these behaviours did not tap mothers' explicit linguistic representation of their infants' mental states. At 54 months, children's understanding of mind and emotion was measured through a range of false-belief tasks and an emotion-understanding task. Multivariate analysis revealed direct positive links between mothers' sensitivity to their infants' internal states and children's later understanding of mind. (Contains 4 tables.)