Preschool-aged children with or at risk for attention deficit hyperactivity disorder (ADHD) experience significant challenges with behavioral, social, and preacademic skills. Kern et al. (2007) examined 12-month intervention outcomes for 135 children, aged 3-5, with or at risk for ADHD. Two interventions, parent education alone and parent education plus functional assessment-based home and school intervention, were compared. Few group differences were found. In the current analysis, an expanded number of outcome measures were examined, including ADHD symptoms, direct observations of child behavior, academic skills, parent variables (e.g., stress), and treatment acceptability. Maintenance of treatment effects across 24 months was also examined. Although no group differences were found, statistically significant improvements for 27 of 46 outcome variables were obtained, indicating that parent education alone was effective. Parents and teachers reported intervention to be moderately acceptable. The findings suggest a tiered approach to intervention may be necessary for optimal outcomes. (Contains 2 tables.)