Los Osos High

Set in Rancho Cucamonga, California, Los Osos High is a sprawling 9-12 campus, part of Chaffey Joint Union High. It works with 2,759 students across grades 9 through 12. Compared to the state average of about 838 students per school, that is 229% above typical.

Los Osos High is one of 11 schools operated by Chaffey Joint Union High, a district that works with 22,040 students overall.

On demographics, Los Osos High reports that the most-represented group is Hispanic (41%), with the rest of the student body spread across multiple groups. Beyond that, the school logs 24% White, 23% Asian, 6% Black, 5% multiracial. That is considerably less Hispanic than the county at large, where the share is closer to 55%.

On the resource side, On paper, Los Osos High has 107 full-time-equivalent teachers, translating to a class-load average of around 25.8:1. Statewide, the average ratio sits near 18.2:1, putting Los Osos High higher than the state norm the norm. Roughly 44% of students at Los Osos High qualify for free or reduced-price lunch, a commonly cited indicator of low-income enrollment. Set against San Bernardino County (around 74%), the school's rate is meaningfully below typical.

After controlling for student poverty, Los Osos High tracks the demographic baseline. The model predicts 53.5% given the school's FRL share; actual proficiency is 65.2%.

In the broader community, ACS estimates for San Bernardino County put median household income runs about $85,478, 23% of adults hold a bachelor's degree or higher, and the poverty rate sits near 11%. Los Osos High is one of 583 public schools in San Bernardino County (combined enrollment of about 393,648 students).

The closest other public school is Caryn Elementary, roughly 0.4 miles away. 8 of the 8 nearest public schools sit inside a five-mile radius. Among the 9 schools in that immediate cluster with test data (this one included), Los Osos High ranks 5th on composite proficiency, below the local average of 67.7%.

Geographically, the school is in an outer-ring area.

Looking at the recent track record. Over the past 7-year window, the student count edged down 12%: 3,153 students in 2018 compared to 2,759 in 2025. White enrollment moved from 35% to 24% across the same window.

Inside the community feed, the feed for Los Osos High typically covers enrollment questions, classroom assignments, and PTA news. Parents, students, alumni, and staff are welcome to weigh in.