In recent years, exclusion rates on PISA have risen in many countries, including a sharper-than-average rise in Norway. This thesis focuses on Norway's experience with exclusion rates in PISA, including an analysis tracking this increase between 2000 and 2015. The research draws on theoretical perspectives highlighting how the globalization of educational governance and assessment has led to increased international competition and pressure for good results. In addition, this thesis explores several ideas that might explain why Norway's exclusion rates have risen. A qualitative case study has been carried out in a municipality in Norway. The analysis is based on interviews with PISA Norway team members and select Norwegian school leaders. During interviews, school leaders also took part in an exercise to practice applying the PISA exclusion guidelines. Key findings revealed that there is a distinction between using the terms "exemption" and "exclusion" in Norway. Additionally, although guidelines and training have become clearer over the years, there can be confusion between the exclusion guidelines used in PISA and on national tests. Interviews also revealed a high degree of school leader subjectivity in determining student participation, and that many school leaders made decisions to promote student feelings of mastery and minimize feelings of defeat. Recommendations include ideas for how to change future PISA training sessions for school leaders to address these issues and reduce student exclusion.