The one thing you all seem to forget is that differet states have different age cutoffs for Kindergarten. In LI it is Dec. 31 and in MD/VA most districts are 9/1. So if your kid is a July/Aug birthday you might hold them back then so they are better prepared for school. Very few kids are held back after that. The difference in the cutoff dates makes more of a impact than you think. On my sons team which is one of the teams mentioned there is only one kid that was held back after kindergarten or reclassed.