The overarching goal of this research project is to conduct a randomized efficacy trial of a preventive intervention—the Kids in Transition to School (KITS) program—to enhance socioemotional and academic school readiness among preschool-aged foster children. Foster children are at great risk for poor social and academic school outcomes. Because of their experiences of early adversity, these children may have particular vulnerabilities that decrease the likelihood of a successful transition to school. Extensive prior research has shown that chronic early adversity is associated with alterations in the functioning of key neural systems (specifically, prefrontal cortex function and hypothalamic-pituitary-adrenal axis activity) related to self-regulation and stress reactivity. Alterations in these systems may interfere with children's abilities to relate to peers, to maintain focused attention, to follow directions, and to learn academic skills. Additionally, because these children are likely to have experienced multiple living transitions, they may be at a disadvantage in terms of caregiver involvement in school, a critical aspect of early school success. Foster children are recruited in the spring before they enter kindergarten and randomly assigned to the intervention and comparison conditions. The KITS intervention includes three components: (a) child therapeutic play groups to facilitate the development of self-regulatory, social, and emergent literacy skills; (b) a psychoeducational support group to promote caregiver involvement in the child's emergent literacy and schooling and the use of effective parenting techniques; (c) home- and school-based behavioral consultation. The intervention coincides with the transition into kindergarten. Multi-method, multi-agent assessments of the children's socioemotional readiness and literacy skills are conducted at baseline, kindergarten entry, and postkindergarten. We will examine the direct effects of the intervention on school readiness and kindergarten outcomes. We will also assess whether intervention effects are mediated through mechanisms of stress reactivity and regulation and caregiver variables. Finally, we will test for moderator effects of child and contextual characteristics including early adversity (prenatal/neonatal health, maltreatment history and placement history), child cognitive functioning, and placement transitions during the course of the study. An additional exploratory aim of the study is to examine intervention effects on first and second grade outcomes for subsamples of children. Group comparisons and longitudinal growth modeling will allow for evaluation of hypotheses.