This thesis is a part of a pilot project, “Disorder in School”, which are led by Professor Liv Duesund. It is a case study, where the purpose has been to examine what characterizes a third grader’s inappropriate behavior. The study is based on observations, and we found it crucial to look at environmental factors along with our observations and interpretations. Our study seeks to answer the following research question: What characterizes a pupils’ inappropriate behavior during school hours? We have developed two research questions in order to answer our main research problem. a) What is characterizing the situations where the pupil shows inappropriate behavior? b) Which factors seem to provoke the inappropriate behavior? Our intention has been to identify inappropriate behavior during school hours, and examine the contextual factors that seem to influence in the occurrence of the inappropriate behavior. According to the large scope of disorder and behavior problems in today’s school, this phenomenon is in need of more attention and investigation. We have used qualitative observation to study our phenomenon inappropriate behavior, and we have used a pre-structured observation form developed by the project. We have conducted five observations of our target pupil. Four of them have been carried out during class and one has been carried out during a recess. Based on our observations conducted in class we have classified the pupil’s inappropriate behavior in four different categories. Our data collection and interpretations show that the target pupil’s behavior was mostly characterized as physical and verbal agitation at desk or seat on carpet on task. There was also a considerable amount of behavior coded as wandering in classroom without interfering with others. In spite of our target pupil showing a lot of physical agitation, he still seemed to be on task when exhibiting this behavior. Another significant finding was how the environment related and responded to his behavior. We found that the other pupils did not seem to be disturbed by this type of behavior, and in fact they did not seem to pay much attention to what others did at all. The teacher neither seemed to be occupied by keeping order, quietness and uniformity at all times, such as raising hand before speaking and asking for permission to go get up from their seats. We did not see as much inappropriate behavior as we expected to see. Instead of seeing a lot of factors provoking inappropriate behavior, we saw a lot more factors that contributed and initiated to appropriate behavior. We found the teacher’s classroom management, which was based on a positive behavioral support approach, to be very good. Several environmental supports were implemented in our target pupils’ school day, and he seemed to respond very well to these supports. The environment seemed to be meeting his needs, and we saw these factors to be vital to the lack of disorder in this classroom.