The whole "double holdback" argument is an urban-myth. My kids have been playing lacrosse for well over a decade now, and I have yet to encounter a double holdback. Yes, it is true that the age cutoff for most of the country outside the LI area is 9/1. And yes, it is true that most of the top, most prestigious independent schools strongly encourage boys with summer birthdays (and by summer, I really mean July or August) to do pre-K or kindergarten x2. Trust me, it had nothing to do with lacrosse. (BTW, if you read Outlier, and you were going the private school route, you would have held back your son too.) When your son plays grade-based lacrosse, it is not cheating to play with his grade. What young boy wouldn't want to play with his friends from school, instead of a bunch of strangers from the grade above?