Size small runs like a size 3-4 not a size 5-6 . So if you are a xs and a size 3-4 this size small is good for you. I also imagine xs runs like a size 2, so anyone 0 could consider xs as an xxs.  I ordered a medium just now to see how it fits before returning this small one to see if it runs like a size 5-6. I am always a size small (4-6) so I know my measurements well. If you are always a particular size and not sure order it in both sizes and return one or size up. Also I am petite 5'2 so if you are taller, I'm not sure it will fit you on your ankles or like a capri. I love the pants they are perfect just hard to put on if it is not your actual size. Hope this helps.

FYI Sorry I updated on the wrong one when I get this in medium I will make sure to give it a new rating if it works out the way it should. :)