The development of nuclear weapons, the rise of advanced military technology, and the prevalence of struggles only rarely punctuated by warfare has given birth to communities of civilian defense experts in all advanced countries. In most cases they rely, directly or indirectly, on the analytical techniques described herein, set down at Rand and rooted in the Anglo-American mobilization of scientific and analytical talent for two world wars. At the heart of this enterprise lay the attempt to measure with rigor and, wherever possible, numbers the effects of military operations and the effectiveness of military organizations. The authors of these essays -- including Albert Wohlstetter, Thomas Schelling, C. J. Hitch, and Quade -- were some of the pioneers in this work. Time has revealed the weaknesses and inadequacies of some of these approaches but has not diminished their hold on the minds of civilians and, now, many soldiers as well.