This study tests a mediated model of boys' and girls' weight status and math performance with 6,250 children from the Early Childhood Longitudinal Study. Five data points spanning kindergarten entry (mean age = 68.46 months) through fifth grade (mean age = 134.60 months) were analyzed. Three weight status groups were identified: persistent obesity, later onset obesity, and never obese. Multilevel models tested relations between weight status and math performance, weight status and interpersonal skills and internalizing behaviors, and interpersonal skills and internalizing behaviors and math performance. Interpersonal skills mediated the association between weight status and math performance for girls, and internalizing behaviors mediated the association between weight status and math performance for both sexes, with effects varying by group and time. (Contains 5 tables and 1 figure.)