I live in the Southern California mountains and these wooly Crocs are the BEST!!!  I was actually outside shoveling away nearly 3 feet of snow and totally forgot I had my Crocs on.  Well, my feet were completely warm and toasty even after an hour standing in the snow in 27 degree weather!!  Now THAT'S a miracle shoe if you ask me!  The reviewer who recommended you go a size UP rather than down for 1/2 sizes was right.  I wear a 6-6 1/2 and ordered a size 7...and it fit perfectly.  I KNOW the size 6 would have been too small.  These work great WITH or WITHOUT sox.  I highly recommend these shoes.