The purpose of this paper is to discuss the topic in my thesis: girls` and boys` interaction in school, focussing on their language use. An important starting point for the thesis is a pilot study, an interview with girls at an intermediate level. It shows that the girls interpret the boys to be setting up the agenda for their behaviour. My recent ethnographic study, however reveals a different scenario. A participant observation study in three different classes over a period of six weeks, shows that both girls and boys use a sexualised language. Boys use it in public addressing both girls and boys, mostly in situations where performance and competition are central. Girls use it mostly when addressing others girls in private rooms. These observations even show that when girls are together, they set up an agenda for themselves for their behaviour as well as for what kind of clothes and make-up to wear.