Born into an Army family at Fort Wadsworth, New York, Rebecca Craighill Lancefield became interested in scientific studies while an undergraduate at Wellesley College. She earned her Ph.D. in immunology and bacteriology at Columbia University, where she was a student of Edmund Beecher Wilson and Thomas Hunt Morgan. While at Columbia, she also worked at the Rockefeller Institute, later to be known as Rockefeller University. It was at this institution that she became a professor of microbiology.
Her basic research was concerned with streptococcal infections, and her work came to be known as the Lancefield classification system of these infections.
Prior to her findings, the medical world had believed that each type of clinical infection (e.g., scarlet fever, sore throat, erysipelas) was caused by a streptococcal bacterium that was specific for each infection. Dr. Lancefield demonstrated that one group (Group A) of streptococcal bacteria could cause these diseases. Her system of classification of the more than sixty types of Group A streptococcal bacteria continues to be invaluable in the identification and treatment of streptococcal infections. Her outstanding work was also recognized in her election to membership in the National Academy of Sciences.
Her association with the Marine Biological Laboratory began early in her career. In 1920, she was listed as a Beginning Investigator in Zoology. In 1926, she was an Independent Investigator in Zoology. At that time, she was an assistant in the Department of the Hospital at Rockefeller Institute. Her summer attendance at the MBL continued in an almost unbroken line for the remainder of her life. She and her husband, Dr. Donald E. Lancefield, maintained a home in Woods Hole, and both chose to be buried here in the cemetery of the Church of the Messiah.