Children progress through various landmarks in their understanding of mind and emotion. They eventually understand that people's actions, utterances, and emotions are determined by their beliefs. Although these insights emerge in all normal children, individual children vary in their rates of progress. Four lines of research indicate that language and conversation play a role in individual development: (a) Children with advanced language skills are better at mental-state understanding than those without advanced language skills, (b) deaf children born into nonsigning families lag in mental-state understanding, and (c) exposure to maternal conversation rich in references to mental states promotes mental-state understanding, as do (d) experimental language-based interventions. Debate centers on the mechanism by which language and conversation help children's understanding of mental states. Three competing interpretations are evaluated here: lexical enrichment (the child gains from acquiring a rich mental-state vocabulary), syntactic enrichment (the child gains from acquiring syntactic tools for embedding one thought in another), and pragmatic enrichment (the child gains from conversations in which varying perspectives on a given topic are articulated). Pragmatic enrichment emerges as the most promising candidate. Copyright © 2005 American Psychological Society.