The aim with this paper has been to investigate whether there were any gender differences in texts written by upper secondary students and whether students at this age were aware of gender differences. In order to investigate the aim I carried out two classroom studies. First I asked students to write about the topic “An important person in my life”. Then, I rewrote ten of the texts, which I thought were the least apparent of gender. Two classes of peer students were asked to read these texts and guess the authors’ genders. It was pointed out to them the importance of giving a motivation for their guesses. The results, which included both the peer students’ observations and mine, showed that there were certain tendencies for girls and boys to write differently (vocabulary, complexity, expressing emotions) and about different things (content). Consequently there were indications of differences between boys and girls, even though many of the students’ observations were coloured by stereotyping. The conclusion was, therefore, that the boys and the girls were more alike than different. Nevertheless, many people believe that the differences are bigger than the similarities, because of the stereotypes produced in our society.