We’ve done it both ways. Especially when the kids were younger (preschool and lower elementary grades), we were more likely to invite the entire class. As they get older, however, and have made close friends that are often not in their same class, their celebrations tend to be a little more intimate with just a small group of close friends from different classes or after-school-activities.

I've always invited just my sons' close friends. I'd much rather my boys have a smaller party and be able to spend the time interacting with their friends. I am sensitive to the idea of feelings being hurt but I encourage my kids not to talk about their parties to other kids to lessen that. On the flip side, I'd rather my kid not be invited to every classmate's party. It's just not realistic to go to every party.

For us, it depends on what the requirements of the class are (they tend to either require inviting all of the boys/girls, or the entire class).