This research investigated the moderating effects of children’s negative emotionality, activity and sociability on the relation between maternal parenting stress and children’s behavior problems. Participants consisted of 1,667 preschool children from the fifth wave of the Panel Study on Korean Children. EAS was used to measure the children’s temperament. Mothers reported parenting stress and children’s behavior problems. The results revealed that the magnitude of association between relation between maternal parenting stress and children’s behavior problems was greater for high levels of negative emotionality and activity as well as low levels of sociability. The results support a diathesis-stress model in which high negative emotionality, activity and low sociability confer vulnerability for preschool children in a high stress family.