The requirement for membership in the American Legion are service in a branch of the U.S. military during one of seven wartime eras, including current active duty. The war eras that American Legion designates for membership eligibility are World Wars I and II; Vietnam; Korea; conflicts in Lebanon, Grenada, Panama and the Persian Gulf; and the War on Terror.
Members of the U.S. Armed Forces who served during one of the designated wartime eras are eligible to join the American Legion, unless they have been dishonorably discharged from their military branch. The American Legion makes the exact dates of the eligible periods available on the application portion of its website, and makes note that any member of the Merchant Marines is only eligible if he served during World War II. As of 2015, the American Legion notes that the ongoing nature of conflicts from 1990 to the present allows eligibility for all veterans who serve during this period.
The American Legion also offers membership to the American Legion Auxiliary and the Sons of the American Legion groups. The Auxiliary is open to all female immediate family members of veterans eligible for the American Legion, while Sons of the American Legion is open to all male immediate family members of eligible veterans.