Previous studies have found that adverse effects of maternal employment on child obesity are limited to mothers with higher education and earnings. Explanations for this have centered on differences between the childhood nutritional and exercise environments provided by non-parental caregivers versus by the mothers. The present study explores this non-parental care mechanism in a quasi-structural model of employment effects on child obesity transmitted through cumulative months of non-parental childcare over the child's pre-school years. Consistent with previous work, it finds that children age 2-18 whose mothers have 16 years or more years of education have a 1.4-1.9% higher risk of obesity for each year of non-parental childcare. Additionally, however, it estimates that children whose mothers have less than 12 years of schooling have a 1.3-1.8 % lower risk of obesity for each year spent in a non-parental childcare setting. It interprets this new finding as due to positive selection into the workforce on ability in both home and market work.