Abstract
This paper presents a model for the explanation of examination (GCSE) performance at the age of 16 years in terms of both secondary and junior school attended together with prior achievement measures and certain background factors. Using a cohort of 758 students in 48 junior schools and 116 secondary schools it compares the variation in performance due to secondary schools with that due to junior schools in a multilevel cross‐classified analysis. It shows that the variation among junior schools is substantially larger than that among secondary schools. It also demonstrates that those junior schools with high average achievement scores for the students when they leave junior school also tend to have high average scores for their students at the age of 16. The implications of these findings, if replicated, are profound. They imply that current attempts to measure the ‘effectiveness’ of secondary schools using achievement measured at the start of secondary schooling may be fruitless and they point to the need for school effectiveness research to become involved in very long term studies of schooling, rather than being restricted to a single phase.