After an extensive search of literature by and about the military profession and professional military officers, this study concludes that the concept of Duty includes five imperatives: defense of the United States, support of the government in the performance of its constitutional duties, dedication to the military profession, selflessness, and courage. As the officer applies these five imperatives in his professional life, balance is essential. For example, it is every officer's Duty to seek in his or her professional life a balance between the competing demands of self and selflessness. This thesis finds the definition of Duty in FM 100-1 inadequate and proposes a definition of Duty based on the five imperatives derived from the survey of literature. It contends that the distinction between individual and institutional values in the Army Ethic dilutes the power of a time-honored word like Duty. It also finds that the essential idea of balance is missing from military ethics instruction and that Duty is not addressed as a separate value within the Army schoolhouse. The study recommends a reconsideration of both the ethics curriculum in the Army schoolhouse and the Army Ethic described in FM 100-1 to better account for the importance of Duty in the profession of arms.