Musicologist and music professor Helen (Margaret) Hewitt was born in Granville, New York, on May 2, 1900. She received a thorough academic and musical education on the East Coast and in Europe. She received a bachelor of arts degree from Vassar College in 1921 and a bachelor of music degree from the Eastman School of Music in 1925. In 1926 she traveled to France to study organ with Charles-Marie Widor and harmony with Nadia Boulanger at the American Conservatory in Fontainebleau.
Upon returning to the U.S. she continued her organ studies with Lynwood Farnam at the Curtis Institute in Philadelphia (1928–30) and earned a master of sacred music degree at Union Theological Seminary in 1932 and a master of arts degree at Columbia University in 1933. After further European study with Heinrich Besseler at the University of Heidelberg she completed the Ph.D. degree at Harvard University in 1938.
Hewitt began her teaching career at the State Normal School in Potsdam, New York (1925–28). She later taught at the Florida State College for Women (1938–39) and Hunter College (1942). She was appointed to the faculty at North Texas State Teachers College at Denton (now the University of North Texas) in 1942 and was one of the founders of the doctoral program in music there. She remained on the faculty until her retirement in 1969.
She was best-known for her authoritative editions of two printed music incunabula by the renowned Venetian music printer Ottaviano dei Petrucci, Harmonice musices odhecaton A (1501) and Canti B (1502). Professor Hewitt was the compiler and editor of the first four editions of Doctoral Dissertations in Musicology (1952–65), published under the auspices of the American Musicological Society. She also translated Die Orgelwerke Bachs (Leipzig, 1948) by Hermann Keller (published as The Organ Works of Bach, New York, 1967) and authored numerous articles in musicological journals and festschrifts.
She received a number of honors during her career. She was the first faculty member at North Texas State to receive the Piper Professor Award for outstanding teaching. She was given a Guggenheim Memorial Fellowship for research in Paris in 1947, and Mu Phi Epsilon, an international honorary music sorority, honored her with its Elizabeth Mathias Award in 1972. Upon her retirement Hewitt donated a notable collection of organ music to the university's music library. A variety of additional books, musical scores, recordings, and archival materials came to the library upon her death, in Denton on March 19, 1977. Collectively these materials are part of the Helen Hewitt Collection in the special collections of the music library at the University of North Texas.