Mary Elizabeth Hyde was born April 20, 1870 in Rhode Island. Soon afterward, her family moved to California where Hyde was raised and went to college. Hyde received her A.B. from Stanford University in 1901 and entered the New York State Library School at Albany in September 1902. Upon graduating from Albany, Hyde went back to California where she served as Assistant Librarian and Editorial Assistant at the California Academy of Science Library. From there she moved to a position as Head Cataloguer at the San Francisco Public Library.

In 1914 Hyde was offered and accepted a position teaching cataloguing at Simmons College. (At the time of her employment at Simmons, the library program offered a four year undergraduate degree and a one year certificate). Hyde taught four to five classes a year in cataloguing during her first three years at Simmons. In 1917 Hyde left Simmons to take a teaching position at the New York Public Library School. She remained at the New York Public Library for three years before leaving to take another teaching position at her alma mater, the New York State Library School, where she taught for two years before returning to Simmons in 1923. Hyde remained at Simmons until June 1936. She returned to California shortly before her death in July of the same year.

In the years between 1923 and 1936, Hyde taught one class in cataloguing and bibliographical principles each semester. During this period Hyde remained active in the field of cataloguing, serving as Chair of the A.L.A. Cataloguing Code. At the time of her return to Simmons, Hyde was working on a book dealing with cataloguing principles and methods to extract the "subject elements in dictionary catalogues." Although her book was never published, it was mimeographed and used as a teaching tool for cataloguing classes at the Simmons College School of Library Science.