San Marcos High School is a high school in the North County city of San Marcos, California. San Marcos High School is a member of the San Marcos Unified School District and serves students from San Marcos, Vista, and Carlsbad. Out of the 4 high schools in the district, it the largest in San Marcos Unified by student enrollment at more than 3000 in 2021. San Marcos High School also has a joint program with LCC High School nearby to serve students in the area.

San Marcos High School had a graduation rate of 99% for the Class of 2020. The Academic Performance Index was an annual measure of the academic performance and progress of schools in California. API scores ranged from 200-1,000, with a statewide target of 800. San Marcos High School’s last API score was 857.

San Marcos High School offers several classes and organizations:

San Marcos JROTC is a program run by retired Air Force Major Mark McLouth, and retired Air Force Master Sergeant Michael Lazare. Founded in 2009, the program was created with the intention to promote values of integrity, service, and excellence among students. Cadets enrolled would experience a multisubject program involving aerospace science, physical training, United States Air Force history, military drills, military dress and appearance, and general life skills over the course of the year.

The PACE Promise, a joint program of San Marcos Unified School District (SMUSD) and California State University San Marcos (CSUSM), guarantees CSUSM admission to all district students continuously enrolled in the district from 9th through 12th grade who meet entrance requirements.

• Eddie Sanchez – Professional mixed martial artist, former UFC heavyweight
• Chad Ackerman – Lead singer for the band Destroy the Runner
• Paloma Young – Professional costume designer
• Terrell Burgess – NFL free safety for the Los Angeles Rams
• Emmett Brown – College football quarterback