Protection against the destructive effects of a thermonuclear explosion requires a substantial defense against the light energy, the shock wave, and the radioactive fallout. Each can produce casualties either directly or indirectly as the result of fires and the destruction of property. Obviously, light can be intercepted by dyes and smoke. The amount of such material required per square mile to permit no more than a first degree burn at ground zero from a 10 MT weapon exploding at an altitude of three miles is calculated. The interaction of the heated air with the shock wave and radioactive debris is explored. It is shown that a substantial degree of protection from them should ensue.