My Kid is a mid November baby and instead of holding her back we put her in so her mom could get back to work full time . She is a Principal list student and a A team lax player. Every kid is different and it all depends on the situation. I know boys lacrosse is a contact sport but if your kid is good then they will be playing on Varsity as a 9th grader and play against kids 3 years older. In college with all of the redshirts some will be 4 years older or more.