Academics who trawled through dozens of research studies found only "inconclusive" evidence that bright children were better served by selective schools.
Authors Dr David Crook, Dr Sally Power and Professor Geoff Whitty said differences in the ways pupils' academic achievements were measured at the two types of schools, and the small number of remaining grammars, made meaningful studies difficult.
But Professor Whitty said: "The best published evidence to date suggests that more able children tend to do better in grammar schools and less able children in comprehensive schools. The differences, though, are small."
The performance of selective and non-selective schools is at the heart of the debate over the last remaining 164 grammar schools. Anti-grammar activists in Barnet, north London, Kent, Ripon in North Yorkshire, Sutton in south London and Trafford in Greater Manchester are attempting to trigger the first parental ballots on the future of selection.
Only last month, a York University study of 60,000 GCSE students found the brightest were at least as likely to succeed in a comprehensive as they were in a selective school.Reuse content