Rebecca Craighill Lancefield is best-known throughout the scientific world for the system she developed to classify the bacteria Streptococcus. Her colleagues called her laboratory at the Rockefeller Institute for Medical Research (now Rockefeller University) "the Scotland Yard of streptococcal mysteries." During a research career that spanned six decades, Lancefield meticulously identified over fifty types of this bacteria. She used her knowledge of this large, diverse bacterial family to learn about pathogenesis and immunity of its afflictions, ranging from sore throats, rheumatic fever and scarlet fever, to heart and kidney disease. The Lancefield system remains a key to the medical understanding of streptococcal diseases.

Born Rebecca Craighill on January 5, 1895, in Fort Wadsworth on Staten Island in New York, she was the third of six daughters. Her mother, Mary Montague Byram, married William Edward Craighill, a career army officer in the Army Corps of Engineers who had graduated from West...