Few prospective studies have examined school mobility in children in foster care. This study described the school moves of 86 such children and 55 community comparison children (primarily Caucasian), living in a medium-sized metropolitan area in the Pacific Northwest who were approximately 3 to 6 years old at the study start. Additionally, the effects of moves from kindergarten through Grade 2 on academic and socioemotional competence in Grades 3 through 5 were examined. A greater number of early school moves was associated with poorer later socoemotional competence and partially mediated the effects of maltreatment and out-of-home placement on socioemotional competence. This was the case only for children with poorer early learning skills in kindergarten. Implications for preventive intervention are discussed.