This study uses a school-level longitudinal control-group design to examine how teachers and principals of inspected versus uninspected schools perceive school improvement at their schools. During the phasing in of school inspections in the states of Berlin and Brandenburg (Germany), both inspected and uninspected schools were surveyed with respect to school improvement activities over a 1-year period. The main finding is that principals' and teachers' perceptions of school quality were highly stable, irrespective of the introduction of school inspections. The results show school inspections had a comparatively low impact on the aspects of school quality measured here.