Compliments from strangers + comfortable = win
I usually wear a small, but for something formfitting and made of stretchy fabric, I opted for an XS. It was the right choice. This fit like a glove without being constricting. It was very comfortable and I never worried about it slipping down. I wore it to a black tie industry awards dinner and got compliments from strangers all night. Wish I had more opportunities to wear it!