Parents and teachers--primary socializers across elementary grades--offer potentially differential support mechanisms for children's healthy functioning across developmental periods. Utilizing child, parent, teacher, and observational data from the National Institute of Child Health and Human Department Study of Early Child Care and Youth Development (n = 1,031), we employed a longitudinal path model to examine indirect associations between parents' and teachers' academic influences (i.e., direct parental involvement, the student-teacher relationship, instructional support) and achievement (reading and math) through behavioral engagement at 1st and 5th grades. Results indicated indirect associations linking direct parental involvement (positively, 1st grade only), student-teacher conflict (negatively, both grades), and instructional support (positively, both grades) to achievement via behavioral engagement, after accounting for the co-occurrence of parents' and teachers' academic influences and other child characteristics. School psychologists may opt for interventions focusing on parents' and teachers' academic influence to indirectly effect achievement by promoting elementary school behavioral engagement.