This study examined the interrelationships among parental play belief, household playfulness, kindergarten play behaviors, and social competence in a sample of Hong Kong Chinese children. Participants were teachers and parents of 140 children (52.1% boys, mean age = 4.35). Parents reported their parental play belief and their child’s playfulness through a questionnaire, while teachers reported children’s kindergarten play behaviors and social competence. Multiple regressions and path analytic model revealed that children’s kindergarten social play, rough play, and reticent behaviors were correlates of their social competence; and that children’s social spontaneity, social play, and reticent behaviors act as potential mediators underlying the relationship between parental play belief and social competence. These findings suggest that parents holding positive play belief may promote their child’s social competence by shaping children’s household playfulness and kindergarten play behaviors. They also highlight the utility of promoting parental play belief, children’s social spontaneity, and kindergarten social play. Copyright © 2024 The Author(s).