Research Findings: Previous studies have found that a growth mind-set was associated with optimal learning and well-being outcomes. However, much of this research has been conducted among adolescents and young adults. Relatively little is known as to whether these associations also apply to young children. The present study aimed to examine whether mind-sets are associated with school engagement and subjective well-being in the early childhood context (i.e. first-grade students). A total of 402 Hong Kong first-grade students (219 boys and 183 girls; mean age = 6.69) were recruited. Self-reported questionnaires were administered to assess students' growth mind-set, engagement, and subjective well-being. Structural equation modeling was used to analyze the data. Results indicated that students who endorsed a growth mind-set were more likely to report higher levels of engagement and subjective well-being. Practice or Policy: Our study demonstrates the importance of growth mind-set for optimal functioning among young children. Growth mind-set may need to be nurtured in the early childhood context as a potential pathway to improving students' academic engagement and subjective well-being.