Children's home and school are the most influential contexts in which learning and development occur, especially during early childhood. This paper builds on Bronfenbrenner's ecological theory and Epstein's theory of overlapping spheres of influence to examine school and family connections and their relationships to family involvement and students' achievement gains. We used a nationally representative sample of kindergartners (16,425 students from 864 schools) and found that schools' efforts to communicate with and engage families predicted greater family involvement in school and higher levels of student achievement in reading and math at the end of kindergarten. We also found that, on average, family involvement at school and parents' educational expectations were associated with gains in reading and math achievement in kindergarten. We discuss the implications of our findings for policy makers, researchers, and practitioners. (Contains 4 tables.)