History of Operations Research in the United States Army, 1942-1962 is the first of three planned volumes, each to cover a different time span, that will eventually be integrated into a single formal volume. Operations research (OR) emerged during World War II as an important means of assisting civilian and military leaders in making scientifically sound improvements in the design and performance of weapons and equipment. OR techniques were soon extended to address questions of tactics and strategy during the war and, after the war, to matters of high-level political and economic policy. Until now, the story of why and how the U.S. Army used OR has remained relatively obscure. This comprehensive history offers important insights into the natural tension between military leaders and civilian scientists, the establishment and growth of Army OR organizations, the use of OR techniques, and the many contributions that OR managers and analysts have made to the growth and improvement of the Army since 1942. The upcoming two volumes will take the story up to modern times. This account should be of interest not only to the Army's analysis community, but also to civilian leaders and military commanders and staff officers at all levels.