A Regular Size 16-18. The chiffon cover would accomodate any size, the closer fitting dress underneath the upper layer of chiffon, is closer fitting. IT WAS a size 16-18 Regular approximately because the dress was made for the size of the singer instead of the singer buying a dress of a certain size. So a distinct size cannot be register but suffice it to be called a regular 16-18. See measurements below.   The ONLY PROBLEM with this dress is that the zipper will need replacing -- simply wore down over the years. The Dress dates 1978. TIMELESS if you will notice, it has not lost one bit of the classical and traditionally beautiful design, and as almost ALL dresses that are as classical as the music they accompany, the designs almost or never go 'out-of'style'. One would never know the age of this vintage dress.  This very beautiful evening gown was designed for recitals-oratorio appearances of Classical singers. Perhaps it could be used for other things such as weddings or balls, however it was and remains intended for large stage works not to be zoomed or watched or entered on a 'small' phone screen... the UP-SIZE performing arts -- where the solo singer stands beside a conductor in front of MANY instruments and doesn't hold a microphone while screaming to the rafters and there are many in the audience 'zooming' the whole show -- so dresses needed to pick up light and to flow as artists moved (or breathed as in the case of a classical singer).  It was created for a 'recital-performance' on the Metropolitan Opera mainstage, and even today when opera has almost been shut down by such things as booty-shaking (no pop-musician names mentioned), sometimes to hide a lack of genuine 'echt' TALENT for singing -- Or even by such political forces as this or that contagion which made the BIG concert halls. No, This dress was made NEITHER for the MET GALA where the clothes take the eye off of the 'so-called' artist/art, NOR was it made to be zoomed in a 2 inch x 2 inch screen. This dress frames the art and enhances the artist providing the art.  The chiffon flows when one enters and moves across stage to central point.  There are finished slits in the chiffon around the upper-hip / below waist area where the hands slip through. As she sings a rising passage or gestures a musical passage or even acknowledges the audience, the chiffon follows the movement -- Just have to see it or wear it feel the complete power of it on stage.  It is a BEAUTIFUL dress. Just can't say that enough. Valuable, sequins on silk - silk chiffon --  the highest quality.  No tag, it an original design at Falk and Falk (?) -- and only one generic tag found on an inside seam -- DRYCLEAN ONLY.  The chiffon attached coverlette is called 'umbrella' in this description, because it is round. See images.   The underdress -- sequential sequins on silk has the appearance of being close fitting by viewers, but is a little more loose than it appears so that the singer could breathe a little more freely. MEASUREMENTS:  Chiffon size is almost impossible to measure there is so much of it. Absolutely exquisite the lay it covers the dress so elegantly, one has no idea how much of it is there. It was a tousand dollar dress the year it was purchased in NYC.  DRESS:  across bust 21 inches / across waist 17.5-18 inches inches / Across hips 22 inches ... From Shoulder of chiffon to hem of chiffon laying naturally is about 59-60 inches.  The Dress from shoulder to hem is about 57-58 inches.  The 'built-in' chiffon scarf can tie loosely at back of neck and hang loosely down the back or can be brought around the front a drape over shoulders --- A One-Of-a-Kind -- as artistically aesthetic as the art form it was built to frame.   Shipping includes insurance, most probably signature required, and safe/clean/protective packaging. Will not be placed in a box smaller than its beauty.