Previous work has shown that mothers’ employment is associated with increases in children’s body mass index (BMI), a measure of weight for height. Nonstandard work (working evenings or nights, weekends, or an irregular shift) may also be associated with children’s BMI. This article examines the association between maternal work and children’s BMI and considers the influence of mothers’ nonstandard work schedules. Using data from school‐age children (approximately 8 to 12 years) in the NICHD’s Study of Early Child Care and Youth Development (N = 990), this study found that an increase in the total time a mother is employed is associated with an increase in her child’s BMI; additionally, the association between maternal employment and children’s weight is much stronger at 6th grade relative to younger ages. There was no evidence that maternal or home characteristics or children’s time use mediated these associations, nor was there any evidence that nonstandard work was associated with children’s BMI. Implications for policy and future research are discussed.