I ordered the Small, black vest and I had to send it back as it was too big, even with a sweater under. I am 5'6", 120 pounds. I own the Super 200 fleece pullover in Small and it fits me perfectly, as do all other LLBean clothes that I own in Small. There seem to be a size-problem with women vests, this is the second vest I have to send back because of its fit. A part from the rather big fitting, the vest looks nice, feels very warm and it does feel good against the skin. I just ordered the X-small, let's see what happens!