The purpose of this study was to fill this research gap by investigating school engagement as a moderator between age and school satisfaction in children and adolescents. School satisfaction and engagement are key indicators of student well-being and academic outcomes. However, research has shown declining levels as students aged. This study tested the hypothesis that decreased school satisfaction with age was amplified by declining school engagement. Participants were 3,177 Romanian students aged 10-19 years. The results of the mediation analysis using Hayes' regression method indicated that, while school satisfaction and engagement were positively correlated, age had a strong negative association. The interaction effect between age and school engagement significantly decreased school satisfaction. The findings show that engagement levels and satisfaction start high for 10-12 year-olds then decline. High school engagement was associated with greater school satisfaction, suggesting that it may have a protective effect. This study highlights the importance of fostering school engagement and satisfaction for children's well-being. Promoting a stimulating and supportive school environment can enhance student interest, enjoyment, and outcomes.