Recent research suggests that symptoms of attention deficit hyperactivity disorder may begin to emerge in children at a very young age. Given that early onset is associated with more deleterious outcomes, early intervention is imperative. In the current study, we evaluated the effectiveness of two different interventions with children aged 3-5 years. A multicomponent intervention combined parent education and individualized assessment-based intervention in home and preschool or day care settings was compared with a parent education intervention consisting of parent education alone. Both interventions resulted in significant improvements measured by standardized assessments of behavior and preacademic skills. There were no significant differences between the intervention groups 1 year postintervention. Implications for further research and practice are discussed. (Contains 6 tables and 1 footnote.)