Helmet padding systems are disclosed. One helmet padding system includes a rigid shell configured to cover a top of a user's head and be worn under a piece of headgear. The rigid shell includes a first pair of slots configured to extend in a direction from a back of the user's head toward a front of the user's head when the rigid shell is worn on the user's head. The first pair of slots define a central portion and opposed side portions of the rigid shell. The central portion includes at least one flap extending from the central portion across one of the first pair of slots and covering a first region of one of the opposed side portions of the rigid shell. A spacing pad is positioned within the rigid shell.