The proposed research project focuses on early identification and intervention with children at risk for the development of conduct disorders. We focus on conduct disorder as a mental health problem among children enrolled in Head Start because: (1) conduct disorder seriously affects lifelong social emotional and academic outcomes for children, (2) children in poverty are at increased risk for the development of conduct disorder, and (3) early identification and intervention can prevent the development of more serious conduct disorders in children. The goals of the project are (1) to describe the incidence of significant behavior problems related to conduct disorders among 3 year old children enrolled in Head Start, and (2) to examine the effectiveness of an intervention on the behavior of children identified with emergent behavior problems or at highest risk for these problems. Two studies are proposed. In the first study, 750 three-year-olds will be screened for early indicators of behavior problems and communication deficits that signal increased risk for conduct disorder. Reports of child behavior from parents and teachers, direct assessment of children, and assessments of family support and stress will be incorporated into a systematic screening protocol designed to identify children at risk. Data from the first study will provide information regarding the incidence of behavior problems, allow determination of the most reliable indicators of increased risk status, and be used to explore the specific relationship between early communication development and increased risk for behavior problems. The second study examines the immediate and longer term effects of a preventive intervention to improve children's social behavior and communication skills. A three-component intervention consisting of (1) parent training, (2) classroom intervention, and (3) maintenance training and transition support will be implemented with 45 children identified as high risk for the development of conduct disorders and related behavior problems; 45 additional high-risk children will serve as an untreated comparison group. The outcomes of the prevention effort will be examined in 4 points - immediately after the intervention is completed, 6 months later, 1 year later, 2 years later. The last assessment will focus on academic, social and mental health outcomes at the end of the children's kindergarten year.