This article enquires into the role of gender in the use of different forms of aggression and in the appearance of conflicts within the interactions between students of 12-17 years of age. In order to understand both aspects, the conversational fragments of students and teachers from two high schools are expounded; discourses obtained using a qualitative methodology with focus groups and individual interviews. The results suggest that aggression is used as a tool to solve certain problems between pairs of the same sex, but is also present in relationships between genders as a form of intimidation that tries to influence heterosexual encounters. The aggression between genders adopts subtle and less visible forms than the aggression in pairs of the same sex due to the negative social opinion that exists about forms of aggression directed towards women. The information presented possesses implications for researchers and teachers if we bear in mind that relationships between genders at these ages reflect future relationships as adults. (Contains 2 figures.)