I originally ordered a medium because I am small on top and medium at the waist.  I returned the medium for a small as it was much too large for me.  The small size fits me perfectly.  I love my new coat.  The plum color is growing on me (I originally wanted chili, red, but this color was not available in small).  If you are looking for a true rain coat, keep in mind, this coat does not have a hood.