Over or Under?

Is it better to over dress or under-dress??!? This I feel is a confusing question I have had it told to me both ways, “When going to a party it is always better to over-dress then under” and then again I have heard it the opposite as well. But when in doubt ask Mrs. Post! After some research I have found the answer:

“When in doubt, under-dressing can be safer than over-dressing.”

Well there you have it, Mrs. Post has spoken.