Runs very big!
I was excited to see this dress as i'd bought the sparrow boiled wool sheath dress in xs last year and loved the fit. however, this dress does not fit the same way. the top fits fine, but the waist and the bottom are way too big. i laid it over my sparrow dress from last year, and the bottom is at least an inch wider (two inches, if you go by the total circumference). i'm planning to exchange for an xxs and see if that one fits better.