This is my favorite hoodie of all time.  The material is cotton, which is so nice; it doesn't get static like the polyester fleece. The material is kind of thin which I like because it's not bulky, and I wear these around the house in the winter for an extra layer.  It would not keep you warm outside.  I have 3: one grey, one dark grey and one pink.  The pink is gorgeous, and the greys are great because they match everything.  To give you an idea of how sizes run, I am 5' 5" and about 135 lbs.  I bought the large and it fits with a little extra room-I don't like tight clothes.