There are two phases within this study. In the first phase, 750 three-year-olds will be screened for early indicators of behavior problems and communications deficits using reports of child behavior from parents and teachers, direct assessment of children, and assessments of family support and stress that signal risk for conduct disorder to identify children at highest risk. Data from the first phase will provide information regarding the incidence of behavior problems, allow determination of the most reliable indicators of increased risk status and to explore the specific relationship between early communication development and increased risk for behavior problems.