Book excerpt: This is the definitive work on one of the least studied aspects of military history -- the non-commissioned officer. Since colonial America, NCOs have played pivotal roles in the administration, training, morale, and fighting effectiveness of the Army. The author traces the evolution of NCO duties; their rank and insignia; relationship to officers; their training (or non-training); and the professional development scheme initiated after the Vietnam experience which produced the finest non-commissioned officer corps in the world.