Based on other reviews, I settled for a Medium in Chalk Houndstooth. The arm holes are a bit snug, so layering would be limited to more fitted long sleeve shirts underneath (as opposed to another sweater/sweatshirt that would be bulkier).The fit is straight, so if you're looking for something form fitting, you may need to consider sizing down, or look elsewhere--this vest does not cinch. I found it spacious around my bust (37") and waist, however it snug around my hips/bum (5'3", 150 lbs; more pear-shaped).This also appears to be more of a shell, like another lining belonged with it, however I'm happy with this purchase for the price at this time. SUPER deep pockets, and a more fitted hood :)