I bought these on a whim because they were crazy cheap.  I love lounge pants... who doesn't?  I'm 5'6" and around 130lbs, so normally a size medium does the trick.  I double checked on Columbia's website, and they confirmed my idea to order a medium.  Big mistake.  Their medium is really more of a large.  They easily fall off of me unless I fold the waist band over.  While I still love them, I'd love them even more if I could safely wear them out of the house without worrying about being pantsed.