R. E. Mountain Secondary School, Public secondary school in Willoughby, Township of Langley, Canada.

R. E. Mountain Secondary School is a modern school building in the Township of Langley featuring flexible classrooms, two gymnasiums, and an open-style auditorium. The campus includes an outdoor learning space designed with an amphitheater for educational activities.

R. E. Mountain Secondary opened in 1977 as a public high school in School District 35 Langley. It moved to a new facility in 2019. In 2014 it stopped enrolling Grade 8 students after Yorkson Creek Middle School took over that grade. In September 2023 it became the largest high school in British Columbia by enrollment, replacing Killarney Secondary.

The school is known for its strong fine arts presence, where students participate actively in choirs, bands, and visual arts courses. These programs shape the daily rhythm and identity of the student body.

The school sits in northern Langley, next to the Langley Events Centre, which supplies extra sports facilities. The Deaf and Hard of Hearing program that once operated here is no longer run as a separate program, so visitors looking for it should contact the district. Access is by road; the campus is busiest during class hours.

Since 2023, the school has been the largest secondary school in British Columbia by student enrollment. This size allows it to offer a wide range of programs and activities.