Innovative lightweight radiation shielding materials are enabling to shield humans in aerospace transportation vehicles and other human habited spaces. Multifunctional materials which provide non-parasitic shielding as well as structural performance is needed. Boron can provide neutron and cosmic radiation shielding, but the only available boron fiber is a large diameter monofianant on a tungsten substrate whose high Z number preclude it use in radiation applications. This program will develop boron fibers on carbon (low Z no.) fiber tow substrate utilizing an existing system for spreading carbon fiber tow and chemically vapor depositing (CVD) coatings. Processing will be optimized to produce high strength boron fiber tow which will be utilized in select polymer matrix composites to demonstrate the multifunctionality of structural and radiation shielding.