I bought a large because it said slim fit and I have long arms. It is big on me and I probably could have gotten the medium. I am not a big girl though. Since it is a bigger fit, I know I could wear something bulkier underneath and it would fit over it. Other than that I life it...how can you complain when it is a nice dark brown color, which is hard to find...and it is 100% cotton.  That was the main reason I purchased it!! Cheap polyester is becoming too common in our clothing. It is horrible since our skin cannot breath in polyester and it is bad for the environment.