Rather belatedly, the United States Army in preparing for World War II investigated on an intensive and very large scale the chemical munitions that might be necessary or useful in fighting the Axis powers. This effort required the collaboration of a host of civilian scientists and research centers as well as a great expansion of the laboratories and proving grounds of the Chemical Warfare Service itself. A similar development, recounted at the beginning of this work, came too late to influence the outcome of World War I. In World War II, on the other hand, the Army not only prepared against gas warfare sufficiently well to discourage its employment by the enemy, but also developed a number of new chemical weapons that contributed materially to victory. The authors add perspective and interest to their story by telling very briefly about corresponding German and Japanese activity. The manufacture of chemical munitions in quantity was possible only through a rapid expansion of private industry to support and supplement the work of Army arsenals. Both necessity and choice led the Chemical Warfare Service to make widespread use of small industrial concerns throughout the United States, and the account of production in this work is especially pertinent to a consideration of the problems involved in military contracting with small business on a big scale.