I sized up and went with the medium. The shorts are VERY short/small and the shirt seems to run almost true to size. It looks like I have no shorts on with it at all. I also expected the pjs to be a more silky feel, but they do feel better on than when you are just touching them. They are the comfy pjs I like to slip on at the end of a long day. The only reason for the 4-star rating is due to the difference in fit of the shirt in comparison with the shorts.