The Kaiser Permanente Medical Care Program evolved from a series of major construction projects in the 1930s and from the World War II shipyards in the early 1940s. In the late 1940s, it became a community-based medical care program, and later in the 1970s, the prototype Health Maintenance Organization (HMO). Over the past five decades, Kaiser Permanente has developed its basic principles of prepaid, group practice for comprehensive-care services where physicians control their medical practice in a partnership of responsibility for the Health Plan, the Hospitals, and the Medical Groups. All of this is carried out with autonomy of its 13 regions in the United States.