These are great, but they definitely run small.  I wear a size 2 jean (5'3" - 107 lbs) and the 6/8 "small" is way to tight.  The rise is to low...gives new meaning to the term "plumbers crack"!!  With just a touch of spandex, it just doesn't give enough movement.  The mediums are perfect for a women who wears misses XS/S. The rise is just below the belly button.  They are just a bit baggy in the legs.  There is no elastic in the waist, just a double band of the fleece.  You could easily add a draw string to the waist.  They are very warm.