Military education programs encompass almost every adult education component from basic skills training through graduate-level higher education. As the country's largest employer, the U.S. Department of Defense (DoD) is also the largest provider of adult education, offering training and education for a workforce of more than 3.2 million members including 1.4 million active-duty military, 1.1 million national guard and reserve forces, and 718,000 civilian personnel. This workforce performs over 800 types of jobs across a broad spectrum of occupational groups ranging from administrative, to health care, to combat-specific areas. To ensure that this extensive workforce is well prepared for the challenges of their important roles in national defense, DoD budgets since fiscal year 2003 have included more than $10 billion annually for training and education programs. Although these programs serve all DoD members, military and civilian, this article focuses on the military learner. Today, training and education programs provide military members a true lifelong learning experience spanning their careers and beyond through in-service continuing professional development, voluntary educational opportunities for self-improvement and advancement, and significant postmilitary educational opportunities. Unquestionably, adult education plays a key role in military education today--as it always has. To meet the military's education needs, the Army, Navy, Marine Corps, and Air Force have all integrated adult learning principles and theory to increase their organizations' effectiveness and address their learners' educational needs. They have also influenced adult education by assisting the field in expanding avenues by which to improve adult education practice beyond the military. Examples include the original conception and implementation of what was to become the General Educational Development (GED) testing program, alternative approaches to help reach learners at a distance, and the assessment of workplace learning for college equivalent credit. Thus, the military educational system provides a fitting lens through which to examine adult education practices and innovations. As a foundation for discussion of these topics, this article provides a historical and contemporary review of the integral role adult education has played for members of the armed services and the continuing efforts by the military to emphasize adult learning principles in training and education. (Contains 1 note.)