I bought the medium, 5'5" 150 lbs, and it fits perfectly. The button and crossover piece are lovely and add to the vibe. It is very comfortable and classy LOVE IT!
Very airy and light cotton. The only problem for me is that the neck is a bit large (it's a Small already), so I will have to fix that, but it's a great sundress and I love the texture, feel and the lovely blues.