Objective: The purpose of this study was to investigate the effect of mothers’ play belief and their children’s play time on self-determination of young children. Methods: Participants of this study were 239 mothers of 6-year-old children attending childcare centers. An online self-report survey method was implemented to investigate whether mothers appreciate the contribution of play on their children s development, if mothers allow their children’s play time, and to examine the level of self-determination of their children. SPSS 22.0 was conducted for descriptive statistics and AMOS 21.0 was used for the path analysis to investigate the hypothetical relationship among variables. Results: Mothers’ play support belief had a direct influence on their children’s self-determination, while young children s play time that was also affected by their mothers play support belief had an indirect effect on their self-determination. Conclusion/Implications: The research shows that children’s self-determination can be fostered by providing time to play when they can make decisions and demonstrate goal directed behaviors, and by providing an atmosphere that emphasizes the importance of playing in one’s childhood.