Since the beginning of the new millennium, the Norwegian education system has shown a growing inclination towards performance-based management. This mixed-methods study aims to gain a deeper understanding of Norwegian primary school teachers' perceptions of the implementation and application of the National Quality Assessment System. The results revealed that teachers' professional agency is influenced by the changes in structure and content driven by performance-based management. The teachers perceived that the national testing process offers valuable insights into students' performance, but it falls short in providing novel information that could enhance individualized instruction. Significant gender differences were discovered concerning the perceived importance, motivation, and influence of national testing on pupils in the primary school setting. This was evident in both the quantitative and qualitative findings of this study. The findings are discussed in light of current educational practices, existing research, and implications for future directions.