The primary objective was to significantly reduce the prevalence of obesity, compared to controls, at the end of the three year intervention. Secondary objectives included maintenance of effects at 6-month follow-up, reducing obesity among high-risk children, improving cardio-respiratory fitness, increasing physical activity, decreasing sedentary activity, reducing the prevalence of unhealthful weight control methods, and improving knowledge, attitudes and perceived self-efficacy regarding the adoption of healthful behaviors. In addition, the investigators identified personal, behavioral and environmental (including family) factors prospectively associated with development of obesity, maintenance of normal weight, weight reduction among overweight children and obesity-related behaviors. Finally, they examined longitudinal changes in height, weight, body mass index (BMI), triceps skin fold thickness, and waist and hip circumferences in girls and boys 8 - 12 years of age, with respect to stages of pubertal development.