Los Osos High School Home

About Us

The Chaffey Joint Union High School District serves the communities of Ontario, Montclair, Rancho Cucamonga, and portions of Fontana, Upland, Chino, and Mount Baldy. With over 25,000 students, the District is the fourth largest high school district in California. It has eight comprehensive high schools, a continuation high school, an online high school, a community day school, an adult school, and alternative programs. The District offers a wide variety of instructional options that provide a quality education for each student, every day. The District's well-prepared, dedicated, and highly qualified teachers and support personnel are second to none.
The Chaffey Joint Union High School District Board of Trustees are steadfast in the belief that "Nothing is more important than student learning and their achievement."
Our daily purpose encompasses our commitment:
"To provide student learning, and ultimately their achievement, of the prescribed curriculum that takes place in the classroom under the direction of the teacher." The Chaffey District supports this daily act. We realize that our efforts uniquely influence the future of our community and of this nation, and we are passionate about doing whatever it takes to prepare students to be successful and contributing citizens of the 21st century.
The Chaffey District has provided a quality education for high school students in the area since 1911. As the District continues to grow and progress, we are poised to meet the challenge of providing the finest quality education possible for every student. 
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All CJUHSD students will graduate ready for college and careers.

Recent News

WeTip - Be the solution


Be the Solution. If you have information regarding crime or misconduct at your school, call WeTip anonymously.

The Chaffey District Cares

The Chaffey District cares about your mental well-being. We partner with community agencies and mental health professionals to provide support to our students and staff. If you, or someone you know, is in crisis please contact the Community Crisis Response Team (909) 421-9233 - Click 'Read Full Story' for more information.

Upcoming Events

School Facts

  • 78% of Los Osos High School graduates meet the University of California and California State University A-G admissions requirements, making it a leader in San Bernardino County.
  • 98% of freshmen at Los Osos High School complete their first year of high school on track to graduate.
  • The CJUHSD has been named a Top Workplace by the Press-Enterprise and Inland News Group.
  • 2500 Advanced Placement exams are administered to students at Los Osos High School annually.

Principal's Message

Eric Cypher
Dear Los Osos High School Grizzlies, Students, Parents, and Families,  
This school year is off to an incredible start, thanks to the wonderful work of our staff, student leaders and parent volunteers! The 2023-24 school year is shaping up to be the best year yet and we remain committed to preparing our students for their road ahead!
At Los Osos we provide many academics supports to ensure our students are equipped with the tools they need to be successful. These supports for students work in tandem with our schoolwide vision that: “All students at Los Osos will graduate ready for college and career.”  Improving our college readiness metric by increasing our A-G completion and decreasing our freshman failures continues remain at the forefront for student achievement. Improving classroom instruction and providing a variety of academic support programs for students will be paramount in accomplishing this vision. Additionally, we have expanded our student support services to ensure that our students have the resources they may need for mental health wellness through our Reach Out program to support our student’s mental health thus promoting their academic success. These ongoing supports continually prepare our students with the resources for meeting their graduation and A-G college requirements.  
As we begin to settle into the school year, I want to remind our Grizzlies that Hard Work Pays Off! We have an entire staff dedicated to guiding you towards your dreams and this staff works tirelessly to see you achieve your success. But remember Grizzlies, it starts with you and that success does not sit solely on the shoulders of the school but with your partnership and your efforts. Success begins with the Grizzly mindset of taking ownership in your learning, displaying that Grizzly Grit through difficult times and asking for help as soon as it is needed. With that said, I challenge all Grizzlies to come to school every day on time, complete all assignments and work hard to pass all classes with a C or higher, ultimately preparing you for college and careers.
Parents, the partnership between student, parent, and teachers is essential to every student's academic success. I encourage you to emphasize the importance of daily attendance with your student, communicate often with our teachers and regularly monitor grades and academic progress through Canvas.  In addition to Canvas, make sure you have created your Parent Square account and downloaded the app to receive up to date communication from our school. Together, we will ensure that your child is successful. For further support, please visit the Parent Resources tab to learn more about these opportunities.
Los Osos High School is an amazing place to be. We look forward to our partnership and another incredible school year! 
Claws Up and Go W.I.L.D! 
Eric Cypher
Principal of Los Osos High School