I was a bit surprised just now when I loaded my game again and went into third person view by accident that my character seemed to be only wearing underwear with a few pieces of armor on top. It turns out that I was mistaken and that you can wear individual armor pieces on top of your actual clothing.
So now I'm wondering how many different slots for clothing and armor there are actually, and which pieces I can wear at the same time.
Best Answer
You can wear an armor piece for each limb plus your chest and head and then a thin garment underneath. This means you can wear your vault suit or some other clothing and have a piece of armor on each arm/leg and your chest/head, and these will be rendered on top of each other when you zoom out. You can also wear some eye wear which can add a further minor boost to stats.
Note that some items of armor will completely remove all other armor (for example the Haz Mat Suit will remove everything and you'll have to put it all back on again afterwards).