The League was founded by Major General John A. Lejeune in 1923 and chartered by an Act of Congress on August 4, 1937. Its membership of over 50,000 is comprised of honorably discharged, active duty and Reserve Marines with 90 days of service or more, and retired Marines. It includes officers and enlisted, both male and female.

The Marine Corps League is headed by an elected National Commandant, with 14 elected national staff officers who serve as trustees. Day-to-day operations are under the control of an executive director who supervises the day-to-day performance of the national headquarters staff, located at 3619 Jefferson Davis Highway, Suite 115, Stafford, Virginia.

The prime authority of the League is derived from its charter and from its annual national convention held in August in different major U.S. cities throughout the nation. The National Commandant has operational control over the National Headquarters staff and the National Board of Trustees, who in turn coordinate the efforts of 45 departments, or state entities, and the activities of over 780 community-based detachments located throughout the United States and overseas.

 
The League is classified as a veterans/military service organization and was formed for the purposes of promoting the interest of the U. S. Marine Corps; to provide camaraderie and assistance to Marines, as well as to their widows and orphans; and to preserve the traditions of the U. S. Marine Corps. It is a not-for-profit organization within the provisions of Internal Revenue Service Code 501(c)(4), with a special group exemption letter which allows for contributions to the Marine Corps League, its Auxiliary and subsidiary units, to be tax deductible by the donor.