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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

Can you believe the 4th quarter is here!  I am so proud of all the hard work you put in this year, but we still have much to do! I want to encourage you to keep the course and finish this year strong! The fourth quarter is extremely busy but a time to showcase your talents and reap the rewards from all that Hard Work Paying Off!  Adversity is something that we continue to over come and we are proud of the accomplishments of VAPA programs, Clubs and sport teams.  Looking ahead we have many activities planned and I can’t wait to see the legacy our seniors will leave! 

As we approach spring break and move into the month of April, please review the following information:  

     -Spring Break: March 25-29  
     - Prom Rally April 5th 
     - Prom April 6th 
     - April 10th Senior Awards families will be notified if receive an award  
     - CAASPP Testing for Juniors/Seniors: April 8th – 19th     
     - April 19th Film Concert and Art Walk 
     - AP Testing beginning May 6th through May 17th.    
     - Spring Season sports (Swim, Track, Baseball, Softball, Boys Tennis, Boys Volleyball and Boys Golf) are                     underway! Come out and support our Grizzlies! 
     - Be on the look out for our performing arts shows with Dance, Choir, Drama and Band 
     - And lastly, Senior Graduation May 23rd! 

There is so much to pack in before school lets out! 
This year’s Summer School will take place June 3rd through July 2nd.  Summer school will consist of two periods to help all students with a D or F to remediate their classes and get back on track.  Any student that had a D or F over the past few years are going to be contacted by their counselor to get them enrolled into summer school. Remediating those D’s and F’s is an integral part of getting back on track for meeting the A-G requirements (minimum requirements for Cal State entrance into college).   
Seniors, your time to shine is ahead!  Now is not the time to lose focus.  I encourage you to finish the year strong and enjoy the senior activities that are planned for you.  Graduation is right around the corner, so keep your eyes on the prize! 
Finish the year strong Grizzlies and keep those Claws Up and Stay W.I.L.D! 

Eric Cypher 
Los Osos High School