The American Cancer Society (ACS) is the "nationwide community-based voluntary health organization dedicated to eliminating cancer as a major health problem by preventing cancer, saving lives, and diminishing suffering from cancer, through research, education, advocacy and service."

The society is organized into thirteen geographical divisions of both medical and lay volunteers operating in more than 3,400 offices throughout the United States and Puerto Rico. Its home office is located in the American
Cancer Society Center in Atlanta, Georgia.

The society was originally founded in 1913 by 15 physicians and businessmen in New York City under the name American Society for the Control of Cancer (ASCC). The current name was adopted in 1945.

The sword symbol, adopted by the American Cancer Society in 1928, was designed by George E. Durant of Brooklyn, New York. According to Durant, the two serpents forming the handle represent the scientific and medical focus of the society’s mission and the blade expresses the “crusading spirit of the cancer control movement."

Its activities include providing grants to researchers, running public health advertising campaigns, and organizing projects such as the Relay For Life and the Great American Smokeout. It operates a series of thrift stores to raise money for its operations. Notable endorsements include the Hopkins 4K for Cancer, a 4000-mile bike ride from Baltimore to San Francisco to raise money for the society's Hope Lodge.