Abstract: A helmet includes a fit adjustment system that is operable to adjust a fit of the helmet about a user's head. The fit adjustment system includes a base member, a tightening mechanism, a tension member, and a plurality of guide members that are attached to an interior of the helmet. The guide members guide the tension member about a path within the interior of the helmet and define a gap within which the user's head is positioned when the helmet is positioned about the user's head. Operation of the tightening mechanism tensions the tension member, which reduces the gap defined by the tension member's path and causes one or more components of the fit adjustment system's components to constrict about the user's head.