This study focuses on the stability and changes in primary school results over an eight-year period, and stems from the tradition of school effectiveness research. To estimate the (in)stability of results, a longitudinal, multilevel design with repeated measurements at school level was used. It shows that the effects of the student background characteristics gender and ethnicity on schooling results changed over the eight-year period. The results of estimating the stability of effectiveness are in line with earlier research and can be judged ‘middling’. About two-thirds of schools and classes approximately retained their position in the rank order of schools. This implies that there is also a certain amount of change which might be related to changes in school characteristics and indicate real improvement or decline in results.