Dunn's motto is the Latin phrase “Ne Tentes Aut Perfice,” which translates to “All or Nothing.” Upon hiring headmaster Tony Dunn in June 1957,[2] The Valley School was incorporated and opened in September that year with an enrollment of 49 children, including 15 girls and boys in nursery-kindergarten, 14 boarding boys in grades 7-10 and 20 coed day students in grades 1–8.

The 6-acre site in Los Olivos was previously home to the Valley Farm School, which was founded in 1949 by Mr. and Mrs. Percy Hodges.

Dunn teaches to its five core values: emotional wellness, physical readiness, intellectual growth, social responsibility and moral courage.

[4] Later episodes included author and former journalist Irshad Manji, Instagram VP of Engineering Maria Zhang,[5] and physicist Tané Remington.

[7] The CBLC is the hub of the leadership program and includes an innovation lab, a student-run café, a college counseling center and space for student study, reflection and collaboration.

Music classes take place in the historic schoolhouse at the center of campus, which is equipped with practice rooms, pianos, guitars, drums and many other instruments, as well as a digital recording facility.

In 2021, Dunn Head of School Kalyan Balaven founded the Inclusion Lab of Santa Barbara County, a joint collaboration between public and independent schools in Santa Barbara County with the expressed purpose of progressing inclusion efforts across the board.

Adopted in the 1970s, the nickname's origin is attributed to an urban legend describing a rush of earwigs exiting a building on campus in its earliest days.

The Dunn boys soccer team has produced both collegiate and professional players as well as multiple CIF-Southern Section divisional championships.

1 overall by the expansion Minnesota United FC in the 2017 MLS SuperDraft after starring for UCLA Bruins men's soccer.

Two players from the 2020 team also joined NCAA Division I programs: Brima Kamara (CSU Bakersfield) and Rene Pacheco (UC Santa Barbara).