Now that I own a few Herve's of my own, I realize that I wore this dress all wrong. If you can zip up this dress by yourself, YOU DID NOT GET THE CORRECT SIZE. This dress should be very form fitting and you do NOT wear Spanx underneath, or even underwear for that matter. It should do the shaping for you. I wore this dress a size too big and I wore Spanx underneath. It was bunchy and I was pulling at it all night, plus the top was too big so the edges of the fabric looked "rippled" (a sign that it was too big). I normally wear a Medium but wear a Small/Ex-Small in Herve Leger. The saleslady at the Herve store showed me how to wear them and they look AMAZING on!! So much that I own a few! :)