This 2-year longitudinal study examined, in a sample of Chinese children (initial M age=11 years), the moderating effects of the peer group on relations between maternal supportive parenting and social and school adjustment. Data were collected from multiple sources including peer assessments, teacher ratings, school records, and maternal reports. It was found that whereas group prosocial-cooperative functioning strengthened the role of supportive parenting in helping children develop social and school competence, group antisocial-destructive functioning undermined the contributions of supportive parenting to children's social and academic achievement. The results indicated the significance of the peer group as a social context for socialization and development in Chinese children.