Technical Abstract: The objective of this study was to examine the relationship between whole grain and fiber consumption, and body weight measures in children 6 to 12 (n equals 3868) and adolescents 13 to 18 (n equals 4931) years old. A combined 1999 to 2004 National Health and Nutrition Examination Survey data were analyzed. Mean body mass index (BMI), BMI percentile, BMI z-score, waist circumference, and prevalence of overweight/obesity were compared across categories of whole grain consumption (0 to less than 0.6, greater or equal to 0.6 to less than 1.5, greater or equal to 1.5 to less than 3, and greater or equal to 3 servings) with (1) a sex, ethnicity, and total energy intake–adjusted model and (2) a cereal fiber plus model 1 covariates profile. Our results showed that mean whole grain intake was 0.59 and 0.63 servings/d among children 6 to 12 years and adolescents 13 to 18 years, respectively. In children, consumption of $3 servings of whole grain was not associated with body weight measures; however, consumption of 1.5 to less than 3 servings was positively associated with all weight measures. In adolescents, BMI z-score was significantly lower in the highest whole grain consumption group compared with the lowest 2 groups; BMI percentile and waist circumference (model 1 only) were also significantly lower in the highest whole grain consumption group. From this study, we concluded that the overall consumption of whole grain was below current recommendations of at least 3 servings per day. Only in adolescents was this level of whole grain intake associated with lower BMI z-scores.