Healthy Marriage programs in the United States aim to promote marriage primarily among low-income individuals. There is little research assessing whether children fare better when their never-married mothers get married. The present study uses the Early Childhood Longitudinal Survey–Birth Cohort to test the hypothesis that children have higher literacy scores when their mothers who had never married when the children were 9 months old had married when the children were 48 months old (N = 2,800). A small positive effect was found, but only when marriage was compared with cohabitation. The association between marriage and literacy is partially explained by mothers' increased household income. The children of mothers who were single noncohabitants or married and then divorced or separated were also doing better with respect to literacy than children of cohabiting mothers. Future research is needed to better understand how cohabitation is associated with negative effects on children's literacy.