I just got my Expedition Parka. I am 5'7",and 135 lbs. I got a Medium. It's a bit large on me,but that's what I expected. I didn't plan on wearing this coat around the city,with just a T-shirt under it. If I had,I would have gotten a Small. With my normal wool shirt and vest under it, it's just right. The arms are a bit long,but I have that problem with just about any clothes I get-with gloves or mitts, this won't be a problem. To me,the fit is the same as my "Medium" US military N3B coat (but half as heavy). The left-side zip will take some getting used to.