Large and thin
I bought this for an upcoming conference and was grateful that it shipped very promptly.

it runs quite large, in my opinion. i'm 5'7" and about 130-135lbs. the small was huge on me in the chest and shoulders/arms. the stomach also wasn't very fitted. the material is thinner than i expected (you can see through the dress to some extent when you hold it up to the light), but i don't think this is a problem, necessarily. had it been thicker, it probably would be too warm. but you might need a slip