Research on physical aggression often points to teen motherhood as being a primary contributor in the development of aggressive tendencies among young children. As a result of poor parenting practices, limited education, and a lack of emotional, physical, and financial resources, children born to young mothers often exhibit high levels of aggression across the life course. Meanwhile, unintentional pregnancy and young motherhood are likely to share many of the same risk factors and negative consequences for offspring, yet there is a dearth of research examining pregnancy intentionality and offspring aggression. Using the Fragile Families and Wellbeing Study, our study examines how mother’s age and pregnancy intention status influence aggression among their 5-year-old children. We find that young motherhood and unintended births, despite being likely to co-occur, each provide distinct mechanisms for the formation of aggressive behavior in childhood.