Superwash wool isn't supposed to felt, but it must say 'superwash' on the label. I'm still careful though and turn the item inside out, put in a mesh laundry bag, and wash on gentle cycle with cold water, and hang to dry.
Some wools are okay for handwashing, but again check the label. Usually there is a little hand symbol on the label to let you know to hand wash it.
If you ever have a felting project, the wool must NOT be superwash or it won't felt!