The Health Maintenance Organization Act of 1973 (Pub. L. 93-222 codified as 42 U.S.C. §300e) is a United States statute enacted on December 29, 1973. The Health Maintenance Organization Act is informally known as the federal HMO Act is a federal law that provides for a trial federal program to promote and encourage the development of HMOs. The federal HMO Act amended the Public Health Service Act, which Congress passed in 1944. The principal sponsor of the federal HMO Act was Sen. Edward M. Kennedy (MA).