In my kids' school, the rule is if you are sending invites into school to be distributed, all kids in the class have to be invited in order to avoid hurt feelings. If you only want to invite certain classmates, it has to be done outside of school. I realize that this can be a burden to the parents doing the invite, but it does seem to work well for the kids. This is the reason my kids receive a lot of their invites. If the parent doesn't want to invite the whole class, they usually find me after I drop off my kids or ask the teacher for my phone number who then in turn will ask my permission to give it out. A lot of work for everyone, but the kids benefit by not feeling left out. My kids are small, so I guess this will change as they get older and invites will be handled differently. l choose which parties they go to or say ok to the ones my kids really want to attend.