[5] A volunteer militia of the Commonwealth of Massachusetts, it is not part of the U.S. Armed Forces, but includes veterans and serving military members within its ranks.

With the professionalization[7] of the U.S. armed forces preceding World War I including the creation of the National Guard of the United States and the federalization of officer training, the company's mission changed to a supportive role in preserving the historic and patriotic traditions of Boston, Massachusetts, and the nation.

[6] The headquarters is located on the 4th floor of Faneuil Hall[2] and consists of an armory, library, offices, quartermaster department, commissary, and military museum with free admission.

As the settlements which followed the landing at Plymouth increased and spread, there was no organized military force for protection — only local volunteer companies, which lacked the capacity for joint action or any centralized authority.

The English Government had no standing army, with the only permanent force (other than Royal bodyguards) being the locally organised Militia, in which all able males between 16 and 60 were liable to serve as required for home defence.

Governor Winthrop granted a charter on March 13, 1638,[9] and on the first Monday in June following, an election of officers was held on Boston Common.

Since that time, the company has continued to hold their annual elections on the Boston Common on the first Monday in June by casting their votes on a drum head.

In this armory, the company maintains a military museum with free admission and library containing relics from every war the United States has fought since its settlement.

This school was later renamed the Massachusetts Military Academy and is today designated the 101st Regiment — Regional Training Institute (RTI).

A parade consisting of the AHAC, Massachusetts National Guard (MANG), members of the USS Constitution, Washington Light Infantry (South Carolina), and other historic military groups from across New England participate in the parade from Faneuil Hall to Boston Common.