Ok, in Ash shoes, which are one of my favorites, if I am given the option of the size 38.5, that is my true size in this shoe.  If Ash only offers whole sizes, then I take a 39.  I have close to 2 dozen pairs of Ash shoes, so it's pretty safe to say this.  But this shoe is a mystery.  I am not sure it is because it is a flat shoe or that it is a flat shoe with the enclosed heel.  I ended up with a size 40 in this shoe vs. a 38.5.  It makes it a tad bigger in the front, but I found the sides to be very narrow and I have super narrow feet.....I am glad I was able to find the shoe in a size that fit my foot.  I would give the shoe 5 stars for craftsmanship and style and only 1 star for sizing and the frustration of sending shoes back several times!  Great price too.  It would have a 5 star rating if the sizing wasn't so odd!