Parents experience difficulty helping their children with math at home. Math teachers can provide guidance or materials to parents. Little is known about whether this help from math teachers has benefits for parental support at home and thus contributes to students' academic development in math. The current study examines longitudinal associations between parents' perceived support from math teachers, parental academic support at home (reported from parents and students), and changes in students' intrinsic motivation and anxiety in math. Data stem from ninth and tenth graders (M[subscript age] = 14.49, SD = 0.93, 13 public schools, 56.5% girls) and their parents (N = 157 parent-child dyads). The latent structural equation model demonstrated no association between parents' perceived support from math teachers and their academic support at home. Parents' reported academic support at home was cross-sectionally and positively related to students' perceived parental academic support at home and students' intrinsic motivation. In addition, students' perceived parental academic support at home was associated with positive change in students' intrinsic motivation over the academic year. Furthermore, higher student intrinsic motivation leads to a decrease in their anxiety in math over the academic year.