FAREWELLS

Champion of Gregorian Chant

William Peter Mahrt, PhD ’69

Summer 2025

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Bill Mahrt, a musicologist, enjoyed examining libraries’ medieval and Renaissance manuscripts in a search for musical works to resurrect. Some of what he unearthed hadn’t been performed in centuries. Interpreting and performing that music “requires a great deal of scholarship,” says Eric Tuan, ’12, a former student of Mahrt’s and director of the Stanford Early Music Singers. “It was notated with older forms of music notation that most people today cannot read.”

William Mahrt singing next to a music stand with sheet music on itPhoto: Linda A. Cicero/Stanford University

Mahrt’s deep scholarship, spanning medieval music to the 19th century’s Brahms, paralleled his dedication to directing the St. Ann’s Choir at St. Thomas Aquinas Church in Palo Alto. For 50 years, he led the choir in the performance of Gregorian chant, the sacred music of the Roman Catholic Church. Today’s revival of the chant in parish choirs throughout the world can be traced to Mahrt’s efforts.

William Peter Mahrt, PhD ’69, an emeritus associate professor of music and the founder and longtime director of the Stanford Early Music Singers, died on January 1. He was 85. 

Mahrt, who grew up on his family’s wheat farm in Reardan, Wash., studied piano at Gonzaga University and the University of Washington, earning bachelor’s and master’s degrees before coming to Stanford. His love of Gregorian chant began in a church choir when he was a student. 

In the 1960s, Vatican II reforms led many Catholic churches to forgo the traditional Latin Mass, its liturgy sung in Gregorian chant, for contemporary choir music and a vernacular liturgy. Mahrt worked tirelessly to preserve the chant, holding workshops and lectures around the world. In 1998, he led the Stanford Chamber Chorale through a liturgical tour of England’s Salisbury Cathedral, discussing with the students how music, architecture, and liturgy were intertwined. “Even though he wore the suit and tie and was a tenured professor, he was still a bit of a rebel, and he inspired me to be a bit of a rebel,” says former student  Kerry McCarthy, PhD ’03, now a leading scholar of Tudor music. His decades of devotion to sharing the beauty of Gregorian chant saved it from fading into obscurity like so much of the music he rescued from the library. 

Susan Perkins, one of Mahrt’s two sisters, recalls running into a priest and asking him whether he knew her brother. The priest exclaimed, “That’s like asking me if I know Jesus!” 

Mahrt was preceded in death by his sister Kathryn Brannon. In addition to Perkins, he is survived by several nieces and nephews.


Kali Shiloh is a staff writer at Stanford. Email her at kshiloh@stanford.edu.

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