Extensive literature has compared the effect of selective schools with that of non-selective schools on pupil outcomes in England. However, evaluation of selective systems has been sparse and contradictory. From the perspective of educational equity, this study assesses the potential impact of academically selective school systems on pupils' overall academic outcomes. To do this, we compare pupils' academic performance in a selective system with that in a non-selective system using large-scale national data from England. The results show no evidence of a superior academic effect of selective systems on pupils' academic outcomes. While the general results for the effects of the two systems reveal neither system to be superior, an internal pattern implies negative results from the selective system, from which high performers suffer. The findings collectively imply that maintaining selective systems for compulsory education is unlikely to generate any substantial academic gain.