Learning to regulate aggressive impulses is a significant developmental milestone for preschoolers. To date, there is no consensus about whether rough-and-tumble play (RTP) is positively or negatively related to the regulation of aggression. This study examined the relation of RTP with children's levels of emotion regulation and aggression. RTP of 90 4-6 years old preschoolers was videotaped at the school playground and measured through parent questionnaires at home. Besides the amount (frequency and duration), the characteristics (i.e. dominance and emotional display) of father-child RTP were also examined. In both contexts, more RTP was not related to better emotion regulation in children. At school, RTP with peers was related to more physical aggression. At home, the frequency of RTP interactions was related to more emotion dysregulation and aggression. The display of negative emotions during father-child RTP interactions was related to poorer emotion regulation skills, and higher levels of aggression.