In Singapore, one in three newborns out of citizens was born in a cross-national family with a foreign-born parent. Most cross-national marriages involve lower socioeconomic-status Singaporean men marrying female marriage migrants from less developed Asian regions. We use data from a nationally representative study – the Singapore Longitudinal Early Development Study (SG-LEADS) – to examine the impact of a mother’s migration status on behavioral problems of children aged 3 to 7, focusing on family stress and parenting practices. Results show that compared to children living with two native-born parents, children living in cross-national families with a foreign-born mother had significantly more externalizing behavioral problems. However, the significant differences are fully mediated by adverse family dynamics such as maternal psychological distress, family conflict, greater parenting stress, and punitive parenting practices. The greater externalizing behavioral problems from cross-national families with a foreign-born mother are not directly due to the mother’s migration status. Policy interventions should focus on reducing economic hardship and maternal psychological distress, as well as promoting positive family dynamics and parenting practices, to support the well-being of children in cross-national families.