70s Lace Dress in Blue - Very thin material, my guess is content blend.
Do note you may want to wear a slip or petticoat due to sheer lace areas. Elastic waist and neckline (neckline is fairly loose, elastic could be replace if needed tighter). Ribbon accents.
NO size tag, likely handmade, I estimate a L but please check the measurements carefully to ensure proper fit:
Bust up to 42" / Waist 22-32" - flexible due to elastic / Hips 47" /Length 46" /Bodice length to waist 18"
For off shoulder wear: The elastic at the shoulders is about 18" across unstretched, stretching to 23" across maximum. So that is about 36" around to fit the shoulders to 46" at its tightest stretch.
The arm hole is fairly deep at 12" long from top to bottom. There is elastic at the shoulder so I suppose there is some flexibility there.
Good used condition - you may desire to replace shoulder elastic if it is not right size for you.

This item is sold from an excellent, highly rated vintage boutique.