I think it would depend on the child's age & what the child wants. Some kids only want to invite their special friends, while others want the whole class there, and still others may only want the same-sex children there (eg...all girls or all boys). When my son was in elementary school, parents typically invited either all of the boys or all of the girls to their child's birthday party, but when my son was in middle school (he's 14 now), if a child in his class had a birthday party, the parents usually only invited their child's best buddies, not the whole class. Now, of course, he only wants his best buddies and they do a movie or something like that (and I pay for it, naturally...lol).
at 1:28 PM on Nov. 16, 2009