Based on a two-year and three-wave longitudinal sample of 118 Chinese preschoolers, the present study examined the cross-lagged associations between teacher-child relationships and social competence, and the cross-system generalization of social competence between home and school. At each of the three waves, teachers rated the children's teacher-child relationships and social competence in school, and mothers rated the children's social competence at home. The results showed that high closeness and low conflict in teacher-child relationships at three months after preschool entry (T1) predicted children's social competence in school at the end of the first preschool year (T2). T1 teacher-child closeness also predicted social competence at home at the end of the second preschool year (T3). Although early home competence did not predict later school competence, T2 school competence was associated with T3 home competence. Finally, T2 school competence fully mediated the path from T1 teacher-child closeness to T3 home competence. (Contains 3 tables and 2 figures.)