The university was founded in 1991 by Major James P. Etter (USMC, retired) as the American Military University.Operations began in January 1993 with the enrollment of 18 graduate students. Initially, the main goal of the university was to meet the unique educational needs of military personnel needing courses in specialized areas, such as counterterrorism and military intelligence, that were not included in typical university course offerings. In the early years, instruction was done through conventional correspondence.
In June 1995 AMU became nationally accredited by the Accrediting Commission of the Distance Education and Training Council (DETC). In January of the following year, the school introduced its first undergraduate programs. In 1998 AMU made the transition from correspondence-based learning to online learning.
In 2002 AMU expanded to become the American Public University System and established American Public University, intended primarily for civilians and public service programs.