This study investigated the effects of maternal employment in times of change in family role
in bringing up children on English achievement of elementary 4th grade students in Seoul using
instrumental variables. We used two instrumental variables. For the first instrumental variable,
we used whether students are the second or third son by birth order and gender of children.
For the second variable, we incorporated whether schools provide after-school day-care service.
We thought that these two variables are positively related to dual-earner status of households.
Study results showed that instruments are relevant because they strongly predicted both parents
working after controlling for family background and individual characteristics. Further, we
demonstrated that two instruments are valid because they are not directly related to English
achievement. Study results showed that maternal employment status are decided endogenously
and thus ordinary regression analysis could underestimate the effects of maternal employment
status on children's achievement in school. In addition, the effect of maternal employment was
found only in students whose family income was below the median level. This study has
theoretical significance because it reveals causal relationship between maternal employment
status and children's English achievement.