I'm usually a size small in shirts but sometimes have to get mediums because I have big shoulders. I ordered this sweater in size SMALL and it's still a bit big for my taste. It fits ok but I would like it to hug my body more. I'm very thin and this is something I always have trouble with when buying anyways. If only they had an X-small size. It's a great sweater and excellent quality. I'm going to keep it. FYI don't wear it as an open sweater, you will show the pockets hanging out all weird and stuff.