Research Findings: Emotion knowledge (EK) enables children to identify emotions in themselves and others, and its development facilitates emotion recognition in complex social situations. Sociocognitive processes, such as theory of mind (ToM), may contribute to developing EK by helping children realize the inherent variability associated with emotion expression across individuals and situations. The present study explored how ToM, particularly false belief understanding, in preschool predicts children's developing EK in kindergarten. Participants were 60 Head Start children ages 3 to 5 years. ToM and EK measures were obtained from standardized child tasks. ToM scores were positively related to performance on an EK task in kindergarten after we controlled for preschool levels of EK and verbal ability. Exploratory analyses provided preliminary evidence that ToM serves as an indirect effect between verbal ability and EK. Practice or Policy: Early intervention programs may benefit from including lessons on ToM to help promote socioemotional learning, specifically EK. This consideration may be most fruitful when the targeted population is at risk.