According to a heuristic model of emotion socialization, the implications of parental reactions to child emotions may vary by child characteristics. Children’s knowledge about culturally bound, emotion display rules may be one of such characteristics, as it may alter children’s interpretations of their parents’ behaviors. The interrelationships among parental unsupportive reactions to child negative emotions, child emotion knowledge, and child social competence, however, have rarely been investigated. The present study examined whether Chinese children’s emotion knowledge moderated the associations of mothers’ minimizing and punitive reactions with changes in children’s peer acceptance, social cognition, and aggression over time. On two occasions separated by about 1 year, data were collected from 330 children, their mothers, and class teachers from 10 kindergartens in Hong Kong, China. The age of children in Wave 1 averaged 4.81 years (SD = 0.38), and 56% of them (n = 186) were girls. Multilevel models indicated that maternal minimizing reactions were not significantly linked to changes in child social competence. But, for children with more knowledge about emotion display rules, maternal punitive reactions were linked to increases in child peer acceptance and social cognition and decreases in aggression over time. Theoretically, findings demonstrated the interplay of parental socialization practices and child individual characteristics in shaping child development. Practically, findings pointed to the importance of explaining emotion display rules to children in Chinese communities and helping children to balance self-expression of emotions with consideration of others’ feelings. Copyright © 2021 APA, all rights reserved.