A five-foot-diameter, spherical, thin-walled, steel shell, simulating a nuclear reactor outer containment vessel, was lined with three different shock-absorbing materials and subjected to internal blast loading from Pentolite explosive charges. Strain-time histories of shell response were measured with strain gages on the outer surface of the shell. Peak strains generated in the lined shells were approximately one-half those recorded with the same shell when unlined. The results suggest the feasibility of increasing the blast resistance of outer containment vessels of nuclear reactors through the use of a suitable lining material.