This study examines the relationship between parental involvement and academic achievement among adolescents and potential mechanisms underlying this relationship. Using data from six waves of the Korean Children and Youth Panel Survey, this study estimated fixed effects models to account for individual-level heterogeneity. Sobel mediation tests were employed to examine the mediating roles of four aspects of school adjustment, namely: (a) academic engagement; (b) compliance with school rules; (c) positive peer relationships; and (d) positive teacher-student relationships. Results revealed that parental involvement is positively associated with adolescents' academic achievement (b = 0.172). Proposed mechanism variables explain approximately 68.6% of the association, with academic engagement being the most salient pathway. The findings highlight the importance of parental involvement in helping adolescents adjust to school environments and improve their academic performance.