At what age did you start inviting friends/classmates to birthday parties? DS will be 3 next month and has been in preschool with the same kids for the entire year. I think the majority of the kids had their birthdays at the beginning of the school year (August/September), so I can see why the class wouldn't be invited since school had just began. Their rule is all boys, all girls, entire class, or no invitations as far as inviting, so I know nobody has had any parties where the kids were invited. Would it be weird to invite the class to our local park/zoo for his 3rd birthday? I guess I'm just a little hesitant about sending invitations since none of the other kids have.