Members of the Marine Corps League join together in camaraderie and fellowship for the purpose of preserving the traditions and promoting the interests of the United States Marine Corps, banding together those who are now serving in the United States Marine Corps and those who have been honorably discharged from that service that they may effectively promote the ideals of American freedom and democracy, voluntarily aiding and rendering assistance to all Marines and former Marines and to their widows and orphans; and to perpetuate the history of the United States Marine Corps and by fitting acts to observe the anniversaries of historical occasions of particular interest to Marines. 

The Marine Corps League perpetuates the traditions and spirit of all Marines and Navy Fleet Marine Force (FMF) Corpsmen, who proudly wear or who have worn the eagle, globe and anchor of the  Corps.  The Marine Corps League is the outgrowth of Marine Clubs established by Marines returning to the U.S. from the trenches of France in 1918. As those clubs grew in size and number, they became more active in the pursuit of objectives that were of interest to their members and in support of the Corps. Founded in 1923 by World War I hero, then Major General Commandant John A. Lejeune, it takes equal pride in its  Federal Charter approved by an Act of the Seventy-Fifth Congress of the United States of America and signed into law by President Franklin D. Roosevelt on 4 August 1937. 

The League is the only Federally Chartered Marine Corps-related veterans organization in the country.  Since its earliest days, the Marine Corps League has enjoyed the support and encouragement of the active duty and reserve establishments of the United States Marine Corps. Today, the League boasts a membership of nearly 61,000 men and women, officer and enlisted, active duty and reserve Marines, honorably discharged Marine Veterans and qualified Navy FMF Corpsmen.  The Marine Corps League is one of the few Veterans Organizations that experiences continual increases in its membership each year. The prime authority of the League is derived from its Congressional charter and from its annual National Convention held each August in different major U.S. cities throughout the nation. It is a not-for-profit organization within the provisions of the 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.