DS was the youngest in his Kindergarten class in the fall, and among the smallest too. He just narrowly made it before the cut off. And I am super glad we didn't hold him back. Yes he's small and immature but academically it would had been a disaster if we had to wait another year. Basically I look at it as "grade skipped by nature" ... it's a skip we never had to fight the school for smile We ended up homeschooling after the first trimester so he can be academically where ever he needs and wants to be but while he was still at school, we were really happy we didn't have to wait another year.