Previous studies have noted that child temperament characteristics, such as aspects of self-regulation, as well as parental feeding practices contribute to children's body mass index (BMI), and have implications for identifying children who may be at risk of being overweight or obese. While studies have considered children's temperament or maternal feeding practices separately, few have considered these correlates of children's BMI jointly or in interaction in relation to children's BMI. The current study included 179 mother-child dyads participating in a longitudinal study. Information on children's impulsivity and inhibitory control was collected when children were 24 months of age. Children's tendency to emotionally overeat, maternal supervision of children's eating, and toddler and maternal BMI were assessed when children reached 30 months of age. Higher toddler impulsivity and emotional overeating, as well as maternal BMI were positively associated with toddler BMI. Inhibitory control and maternal supervision of toddler eating were not directly associated with toddler BMI. However, the main effect of toddler impulsivity was qualified by a significant interaction with maternal supervision of toddler eating. For children high in impulsivity, there was a significant negative association between maternal eating supervision and toddler BMI. For children low in impulsivity, there was a trend level (p = .059) positive relation between maternal eating supervision and toddler BMI. These findings suggest that increased maternal supervision of children's eating may be beneficial for helping children maintain a healthy BMI when they exhibit high impulsivity.