The effects of early maternal employment (employment during the child's first 3 years) and recent maternal employment (employment during the previous 3 years) on 189 second-grade children from low-income families were examined. Maternal employment was related to a number of selection factors. In comparison to mothers who were not employed, employed mothers scored higher on a mental aptitude test and were more highly educated. Both early and recent maternal employment were also associated with measures of the current family functioning: there was less poverty and higher HOME environment scores when mothers were employed. Hierarchical multiple regressions showed that children's math achievement was positively predicted by early maternal employment and children's reading achievement was positively predicted by recent maternal employment, even after controlling for selection effects and current family environment. These results are discussed in terms of possible mechanisms by which maternal employment may affect children's development.