A brief history of civil defense administration precedes analysis of nuclear attack conditions and the influence of protective measures. Damage limitation procedure is explained in terms of--(1) blast effects, (2) radiation doses, (3) geographical fallout distribution patterns, and (4) national shelter needs. Major concept emphasis relates to--(1) lifesaving potential of improved strategic defense programs, (2) functional protection factor determination for shelters, and (3) geographic and demographic characteristics of hypothetical attack situations. Extensive substantive data and diagrams are included.