We use data from the Fragile Families and Child Wellbeing Study to examine associations between first-year maternal employment and child outcomes for 3-year-old White, Black, and Hispanic children (N=1483). Results from OLS regressions and propensity score matching models indicate that first-year maternal employment is associated with lower vocabulary scores for White, but not Black or Hispanic, children and with elevated levels of behavior problems for Hispanic, but not White or Black, children. Factors such as type of child care, maternal depressive symptoms and stress, and parenting behaviors (including measures of discipline, nurturance, and provision of cognitively stimulating materials) do not mediate these associations between first-year maternal employment and children's outcomes or explain the differential associations across racial and ethnic groups, suggesting the need to look at other explanations for these associations, as well as the need for better measurement of parenting, especially mother-child interaction.