I would say it runs true to size for a normal shirt but to order one size larger for layering or wear as a jacket. I normally wear a size 4-6/small and ordered both a small and medium of this jacket to try out the fit - I kept the medium since I wanted to layer it and returned the small. This has two buttons, one at the waist and one higher up near the neck. There is no zipper. This jacket also has an inside tie (kind of a wrap style top) near the waist. This tie falls slightly too high for me and I plan to move it down closer to the normal waistline. As another reviewer pointed out, the bottom buttonhole on my jacket is slightly too large and comes open, so I have sewed up the buttonhole slightly to keep it closed. Even with these slight alterations (which may not be necessary for everyone), I absolutely love this jacket and have ordered another in a different color.