Objective: To examine the relationship between body mass index (BMI), and executive functioning in 8–19 year- olds. Method: Participants from the Philadelphia Neurodevelopmental cohort (N = 2, 841; ages 8–19) were categorized by age (2 years) and BMI (i.e., normal weight [n = 1, 647], overweight [n = 510], and obese [n = 684]). Participants were medically and neurologically healthy. Participants were not excluded psychiatric diagnoses. All completed the Penn Continuous Performance Test (attention [ATT]), Letter N-Back (working memory [WM]), and Penn Conditional Exclusion Test (novel problem-solving [NPS]). Results: Individual ANOVA's indicated a main effect for each executive measure such that obese children performed worse than their overweight or healthy weight peers [NPS: F(2, 2841) = 10.31, p < .001, ATT: F(2, 2820) = 10.60, p < .001, WM: F(2, 2772) = 13.52, p < .001. With the ATT test there was no significant BMI x age interaction. Post-hoc analyses indicated that obese children had worse attention across all age groups (8–19). BMI group results, however, were modified by an interaction with age groups for WM and NPS such that, within some age groups, obese children and overweight children were not significantly different, but performed worse than healthy weight peers (NPS ages 8–9 and 16–17; WM age 14–15). Furthermore, there were no significant differences between BMI groups on NPS or WM from ages 10–14 and 18–19. Conclusion(s): Obesity appears consistently related to sustained visual attention (ATT) in ages 8–19. BMI is also related to performance on tests of working memory and novel problem solving, but varies according to age.