An "efficacy trial" evaluated the three-year intervention in a cohort of approximately 1200 3rd graders, in 14 ethnically diverse elementary schools, with follow-up in the 6th grade. 7 schools were randomly assigned to the comprehensive intervention, and 7 schools received an attention-placebo classroom curriculum. Anthropometric measures and assessments of food preferences, cardio-respiratory fitness and self-reported behavior, attitudes and knowledge occurred every six months. Parent interviews occurred annually. Although a careful assessment of effects on parents and the schools was conducted, the crucial question was whether the overall intervention had an impact on student adiposity and behaviors.