Objective: The percentage of obese children in the United States has increased dramatically over the past three decades, particularly among ethnic/ racial minorities. This study sought to examine the impact of a clinical case-management intervention based upon the Transtheoretical Model (TTM) to reduce obesity and increase physical activity in children. Methods: Nineteen obese African-American children ages 8-12 were recruited from two pediatric clinics and were randomized to either a 12-week intervention group or a control group. Dependent variables included body mass index (BMI) percentile, physical activity, and stage of change for the child and parent. Results: In comparison to the control group, the intervention group demonstrated significant decreases in BMI and improvements in daily vigorous physical activity. The children in the intervention group demonstrated movement toward action/maintenance stages of change. Conclusions: A 12-week TTM-based case management intervention can have a favorable impact on obesity and physical activity in African-American child.