Parenting styles act as a risk or a protective factor for the development of aggressive behavior problems in children. Moreover, children with deficits in emotion regulation often show increased aggressive behaviors. Previous studies confirm that parenting style also contributes to the development of emotion dysregulation. The present longitudinal study aims to understand this complex interplay and analyzes emotion dysregulation as mediating variable for the relationship between parental warmth or strictness and aggressive behavior from preschool through elementary school. Additionally, parents' educational level and their unity in parenting were considered as antecedent factors influencing parenting styles. The present path analyses are based on questionnaire data from 442 children and their families. The results show indirect effects for the associations between parenting style and aggressive behavior in preschool and elementary school via children's emotion dysregulation. At the same time, a lower level of education and unity in parenting are more strongly associated with a strict parenting style. Children's emotion dysregulation can be positively influenced by a warm and less strict parenting style, leading to a reduction in problems with aggressive behavior from preschool to elementary school.