Spending just a few hours in the classroom situation as a participant observer, one definitely recognizes "boredom" as one of the main features of this situation. In spite of the obvious relevance of boredom in the classroom situation there is almost no research on the topic of boredom at school. Boredom seems to be a taboo of sorts in school research. The paper first deals with methodological problems concerning the exploration of boredom. How can boredom be analysed by the means of ethnography assuming that the ethnographer himself is not bored? On the other hand in the classroom situation boredom becomes a collective phenomenon. Boredom is shown and is communicated in the context of the students' peer culture. What is the "meaning" of boredom? Analysing ethnographic data, the paper suggests that "boredom" is a powerful sign distinguishing oneself from the specific task or the whole surrounding. Being bored means being detached. Concerning the teacher-student interaction there seems to be a tacit consent about the "normality" of boredom in school lessons. Everybody knows that school is (sometimes) boring, but the problem of boredom may not be made explicit. (Contains 1 figure and 14 notes.)