There has been limited research into how teachers view and respond to relational aggression in girls. The existing research is largely quantitative and questionnaire based and has indicated that gender stereotypes may influence teachers’ perceptions of female aggression. The present study adopted a qualitative approach, using semi-structured interviews to explore how seven teachers (six females and one male) working in a single-sex girls’ school experienced and perceived female student aggression. The results were analyzed using Interpretative Phenomenological Analysis and three themes were identified: the physicality of female aggression, aggression as the presence or absence of control, and community—aggression as a means of expressing belonging. These themes were discussed in the context of the need for a new language of female aggression, which promoted a genuine language of assertion for girls and women.