Policy interest in parental involvement in the U.S. has rapidly grown, necessitating a deeper understanding of how families and schools can partner to promote learning and reduce performance disparities in this country. Matching multidisciplinary theory with growth curve analyses of American children in the Early Childhood Longitudinal StudyKindergarten Cohort, this study found that familyschool engagement (in which school personnel and parents reached out to each other) and familyschool symmetry (in which parents and teachers constructed parallel learning environments) were associated with greater reading gains during the primary grades. Socioeconomically disadvantaged children appeared more at risk from one-sided engagement, and their more advantaged peers appeared to benefit more from symmetry.