I had to send them back twice to get the right size.  They run very big.  I wear a 8.5 and ended up with a 7.  But now after over a year, the 7's are roomy because the wool inside is flattened down.  These no longer provide the fluffy comfort that I want in a slipper first thing in the morning or at the end of the day, so I just bought another kind from LL Bean.