Mary Louise Foster was born on April 20, 1865 in Melrose, Massachusetts. Between the years of 1878-1883, she attended the Girls' Latin School in Boston, MA, and later went on to study Classics at Smith College from 1888 to 1891. After her graduation, Foster taught Chemistry and Physics at West Roxbury High School until 1896. During this time, she was also enrolled at the Massachusetts Institute of Technology in Boston (1893-1895). In 1898, Foster found work teaching Chemistry at Lynn High and Classical School. The next year, she became an assistant researcher in the Lab of Physiology and Chemistry in New York, where she stayed until 1901. In 1903, Foster worked as a research chemist for a professor of Pharmacology at Columbia University, where she stayed on until 1907. While working for the professor, she was also a professor herself in the Chemistry department at the Woman's Medical College of New York (1904-1905). After working at Columbia, Foster was appointed as an instructor at Smith College, where she became an Associate Professor of Biochemistry in 1908. In 1912, she received her Masters' Degree from Smith, and two years later earned her PhD from the University of Chicago. She spent the summer of 1917 at the Rockefeller Institute for Medical Research. In 1918, she became secretary to the faculty at Smith College, a position she held for one year. In 1920, she was offered the position of Director at the International Institute for Girls in Spain, located in Madrid. She stayed there for two years, before returning to Smith as the Chairman of the Committee on Interdepartmental Majors, a position she held until 1927. In 1928, she was appointed a member of the Special Honors Committee. In 1930, Foster returned to Spain to work as the lab organizer at the Institute, in the lab which she helped establish, where she stayed until 1932. It was in that year that she went to Santiago College in Chile to work at the Director of New Laboratories in Chemistry and Physics. In the years that followed, she did a great deal of research, was published numerous times and delivered several lectures in her field. She died June 21, 1960.