In collaboration with a local Head Start program, New York University seeks to examine the development of Head Start preschoolers who engage in high levels of underactive behaviors. Specifically, the objectives for this project include: (a) identifying underactive children in the classroom, (b) quantitatively assessing the children's social and emotional adjustment in relation to social and academic outcomes, (c) comparing the reports of preschoolers peer play at home and at school, and (d) examining parents' and teachers' beliefs related to the development of underactive preschoolers (focusing on immigrant parents). Participants for this study will include 180 three and four year-old Head Start children and their families. Children's behavior in the classroom will be assessed using the Adjustment Scales for Preschool Intervention and competencies in peer play will be measured using the Penn Interactive Peer Play Scales. Children's developmental abilities will be assessed using the Preschool Child Observation Record, Second Edition and the Early Screening Inventory-Revised. Results from this study are expected to add to the existing knowledge base of young, low-income children with mental health needs. In addition, it is expected that this study will assist in supporting the development of underactive, Head Start children and their families.