The American College of Physicians (ACP) is a national organization of doctors of internal medicine (internists)—physicians who specialize in the prevention, detection, and treatment of illnesses in adults. With 130,000 members, ACP is the largest medical-specialty organization and second-largest physician group in the United States. ACP provides information and advocacy for its members as they practice internal medicine and related subspecialties. ACP's mission is to enhance the quality and effectiveness of health care by fostering excellence and professionalism in the practice of medicine. It was founded in 1915 to promote the science and practice of medicine. In 1998, ACP merged with the American Society of Internal Medicine (ASIM), which was established in 1956 to study economic aspects of medicine. Known as ACP-ASIM from 1998 to 2003, the organization then re-adopted American College of Physicians as its corporate name.