This study examined hostility and harsh discipline of both mothers and fathers as potential mechanisms explaining the association between a maternal maltreatment history and her offspring’s internalizing and externalizing problems. Prospective data from fetal life to age 6 were collected from a total of 4,438 families participating in the Generation R Study. Maternal maltreatment was assessed during pregnancy using a self-administered questionnaire. Mothers and fathers each reported on their psychological distress and harsh discipline when the child was 3 years. Children’s internalizing and externalizing problems were assessed by parental reports and child interview at age 6. Findings from structural equation modeling showed that the association between a maternal maltreatment history and her offspring’s externalizing problems was explained by maternal hostility and harsh discipline and, at least partially, also by paternal hostility and harsh discipline. Child interview data provided support for both these indirect paths, with associations largely similar to those observed for parent reports.