A modular chemical/biological headgear system includes a helmet liner of a resilient shock absorbing material that conforms generally to the shape of a wearers head, provides a cavity for removable installation of one or more modular filters in the back, and a duct to convey filtered air from the one or more modular filters to a face mask. The helmet liner may be equipped and configured with a variety of interchangeable modular components including hardened outer shells, communications modules, enhanced chemical biological filters, and the like, to meet a wide variety of operational needs.
