I do the followup call. To me, I really need to know whether so-and-so is/isn't coming. I don't want my kids to keep thinking "Susie might still be coming, so let's wait a little longer before we start..."

If the followup call finds the person IS coming, but misplaced the invite, etc., they're usually apologetic and nice. When the person has not responded, and they don't answer their phone, I leave a message in a nice tone of voice saying something like, "Since we haven't heard from you, we are assuming Susie won't be joining us for Beck's party. Please call us as soon as possible if there's been any confusion. Thanks." What stinks is when the person just chooses to not followup with an answer. When it's deliberate, that's lame.

However, I've accidentally been one of the non-responders, and have been grateful that it was cleared up when they called. In our case, we had meant to respond, but misplaced the card, and didn't realized that we let the respond date go by. I always think it's worth calling.

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"The errors of faith are better than the best thoughts of unbelief." - Thomas Russell