['To investigate the hypotheses that in elementary school students: (1) adiposity and academic achievement are negatively correlated and (2) physical activity and academic achievement are positively correlated.', 'Participants were 1963 children in fourth to sixth grades. Adiposity was assessed by calculating body mass index (BMI) percentile and percent body fat and academic achievement with statewide standardized tests in 4 content areas. Socioeconomic status and age were control variables. A subset of participants (n = 261) wore an accelerometer for 3 days to provide objective measurement of physical activity. In addition, the association between weight status and academic achievement was examined by comparing children who could be classified as "extremely obese" and the rest of the sample, as well as comparing children who could be classified as normal weight, overweight, or obese. Extreme obesity was defined as ≥1.2 times the 95th percentile.', 'The results indicated that there were no significant associations between adiposity or physical activity and achievement in students. No academic achievement differences were found between children with BMI percentiles within the extreme obesity range and those who did not fall within the extreme obesity classification. In addition, no academic achievement differences were found for children with BMI percentiles within the normal weight, overweight, or obese ranges.'] Are adiposity and physical activity related to academic achievement in school-aged children?