The proposed five-year cluster randomized controlled pediatric practice-based trial will compare the effectiveness of two practice-based interventions on improving diet and physical activity and reducing BMI among overweight and obese 8-12 year olds seen in pediatric practice: (1) Fitline-Coaching, consisting of a pediatric practice-based component plus Fitline counseling and workbook, or (2) Fitline-Workbook, consisting of the same practice-based component, but only the family workbook materials mailed over 8 weeks, with no referral to Fitline coaching. Sixteen pediatric primary care practices will be randomized to either the Fitline-Coaching (N=8) or the Fitline-Materials (N=8) condition. Five hundred and twelve parents and their children ages 8-12 with a body mass index (BMI) of > 85th percentile (overweight or obese) will be recruited from the practices to achieve N=400 at 12 month follow-up.