I am a petite 5'-3", 126 pounds. I normally wear small to medium in tops (36D). Tried on Medium in both regular and petite and a Large regular. Both mediums and the large fit. If you want an athletic or tailored fit, go with regular medium. The petite medium was a little tight in shoulders for me. Sleeves were right length in Medium. Large was a looser fit that would be better for layering - although the sleeves were a little long. I purchased the Large in Loden Green. The Juniper Green is a flattering color too. A good deal on sale, would not pay full price for this jacket .