Los Osos High School is a public high school located in the city of Rancho Cucamonga in Southern California's Inland Empire in the United States. It operates as part of the Chaffey Joint Union High School District. The school was named a California Distinguished School in 2013, was the recipient of a Golden Ribbon Award from the California Department of Education in 2017, and was a 2018 U.S. News & World Report Best High School Silver Medalist. Graduates from the Class of 2017 met the University of California A-G admission requirements at a rate of 66.4%, nearly 20% higher than the state average.