Birthday invite question

My son is going to be 4 next month. The past years I have always invited my friends kids to his parties. We see them often and he knows them all well. There are a few friends whose kids I invite just because. I don't know if my son would know one way or the other. Now that he is in preschool, I feel he has a bunch of kids in his class that I know he wants to come. I just don't want to have a huge guest list. We are having it at a place, but the cost goes pretty high the more kids we invite.

So basically my question is, when do/did any of you stop inviting your friends kids to the parties and your DC "friends". My son has 22 kids in his class and everytime we go over the list, he says yes to everyone!

Thanks!

Re: Birthday invite question

We still invite very close friends' kids tha we see on a regular basis to parties. In general, I'd say once they hit kindergarten & you're inviting the class, we pared down the list.