The purpose of this study was to investigate the relationship between parents’ motivations for involvement and children’s academic performance and to examine the mediating role of school-based parental involvement in this relationship. This study also explored the extent of school-based parental involvement. The research method was correlational and of structural equation modeling type. The participants were 384 sixth graders (200 boys and 184 girls) in Lorestan Province aged 11-13 years and their parents (69 male and 315 female ones) who were selected by multistage cluster sampling method in 2019-2020 school year. The results demonstrated that parents' motivation for involvement had a direct, significant relationship with school-based parental involvement and children’s academic performance. Furthermore, the structural analysis indicated that school-based parental involvement significantly mediated the relationship between parents' motivation for involvement and academic performance. Finally, the results showed that parents participated moderately in their children's school events. These findings show the importance of school-based parental involvement in primary schools and play a prominent role in providing evidence and empirical background based on parents' motivation for involvement in developing interventions and educational models to improve children's academic performance.