This research examined the hypothesis that the association between parental involvement and adolescents' school adjustment is in part channeled through adolescents' development of positive teacher-student relationships. Three times over the course of 18 months, adolescents (N = 383; mean age at the first wave of the study = 12.31) completed surveys about their parents' involvement in their learning, the quality of their relationships with teachers, and aspects of their school adjustment, including their valuing of school, school engagement, and perceptions of competence. Parental involvement was associated with positive teacher-student relationships six months later, even when adolescents' prior relationships with their teachers were taken into account. Positive relationships between teachers and students were in turn associated with core dimensions of adolescents' subsequent school functioning, above and beyond their prior school functioning. Teacher-student relationships in part explained the longitudinal association between parental involvement and adolescents' school functioning. Impact and Implications: This research indicates that parental involvement in adolescents' learning is associated with adolescents' perceptions of their relationships with their teachers, with such relationships in turn associated with adolescents' academic functioning over time. Findings highlight the role of parental involvement, which includes practices such as participating in parent-teacher conferences and discussing with children about school, for adolescents' academic outcomes. Practitioners may convey to parents the importance of parent-teacher partnerships, such that parents become cognizant of the value of maintaining frequent and open communications with teachers and school personnel.