In a wide perspective this study deals with the high complexity when assessing students in vocational education, exemplified from Carpenter education in a Swedish Upper Secondary School. The aim was to describe and analyze the view of student assessment among Subject Teachers, Vocational Teachers and Instructors at construction sites. Questions asked were; what procedure does the respective teacher category use when carrying out assessments? What kind of knowledge was valued and what type of criteria did the three categories use when making their assessments. Data was collected in form of deep interviews with three Subject Teachers, three Vocational Teachers and three Instructors. Generally the findings reveal that assessment in vocational education is a very complex task. More specific the findings show that Subject Teachers value specific subject knowledge high while the Instructors prefer more general knowledge. Between those two the Vocational Teacher can be found who has to consider both demands from the school and workplace when making their student assessments. The results also indicate that beside the result from written tests the Subject Teachers take problem solving ability and ambition into account when setting grades. The Vocational Teacher do not value written tests but consider self government, knowledge of the process, quality consciousness, aid facilities and self image as valuable key competences. The Instructors view ambition and self knowledge as most valuable when making their assessments.