Duncan Gillis was named to be the 17th head coach in the history of the Caltech men's soccer program on June 2, 2021.

Gillis is coming off a six-year stint at his alma mater Beloit College, where he was named to the United Soccer Coaches 30 Under 30 Class for 2019-20 while leading the Buccaneers during a period of significant growth. He mentored the program's first player to be named First Team All-MWC since his own sophomore season in 2012 for the team that broke the program record for fewest goals allowed in a season and recorded the second-most wins ever. Prior to becoming the Bucs' gaffer, Gillis spent the 2014 season as a part-time assistant, where he helped design practice sessions, determined training objectives, provided tactical analysis before and during games, and handled additional administrative tasks. He holds a National, Advanced National, and Premier Diploma from United Soccer Coaches, their highest technical certification.

The Salt Lake City, Utah native graduated from Beloit in the Spring of 2014 Summa Cum Laude with a double major in Spanish and Education and Youth Studies and a Philosophy minor. He completed his degree with student teaching at Beloit Memorial High School during the 2014-15 school year, advancing from assisting and observing to full-time teaching.