This study investigated relations between social interaction during infancy and children's subsequent theory of mind (ToM). Findings indicated that children's performance on ToM tasks at 45 and 48 months positively correlated with mothers' appropriate comments on her infant's mental state, but not with attachment security. Mothers' appropriate mental state comments during infancy independently predicted overall ToM performance. Children's verbal ability was the only other independent predictor of ToM performance. (Author/KB)