I always buy my dresses for Toms ware, they're always comfortable and breathable not to mention the silhouettes are basic so you have the ability to dress up with heels, dress down with tennis shoes or sneakers, or meet in the middle with fun summer sandals like gladiators. Anyway, I ordered the xs-s, I am 89lbs and 51. Be aware that the snaps on these are NOT functional, only design. And like many of Toms Ware dresses, they are meant to be tight fitting and does hug the body. On that note, I wore these dresses while pregnant (esp the black ones for work) and they were perfect!