According to one embodiment of the present invention, an improved supplemental protective pad for a helmet is disclosed. In one embodiment, the pad includes a base portion which is mounted to the surface of a helmet shell. The pad is shaped to cover high risk, non-frontal impact areas such as the back of the head and adjacent the sides of the crown of the head. Extending outwardly from the pad are a plurality of compressible and crushable protrusions. The protrusions can be configured in a variety of shapes, sizes and densities to absorb a predetermined amount of force. When the individual wearing the helmet is involved in an impact on one of the impact areas, the protrusions complement any interior cushioning to compressibly absorb the impact force. If the impact force exceeds a predetermined level, the protrusions absorb additional energy while being crushably deformed. When the protective pad has been crushably deformed, preferably the crushed portion is visibly noticeable and the protective pad is replaced.