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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

Unity Conference Flyer

Back to School Unity Conference

A virtual summit designed for families to learn skills in navigating a return to school with focus on valuing humanity while considering the realities of two pandemics. This is a free event and pre-registration is required to attend.

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

Joshua Kirk, Principal
Grizzly Nation,
We are near the end of the school year with our last day being on May 20, 2021.  In addition to that being the last day of the school year, it is also the day of our graduation ceremonies.  Seniors will attend one of two graduation ceremonies on May 20, 2021, one at 3:30 PM and one at 7:00 PM in our Grizzly Football Stadium.
Finals are also around the corner and will be taking place May 17th - 20th.  Please note that due to finals week, Monday, May 17th will be a regular school day schedule and Not just a second period check-in. Seniors will take their finals on the 17th & 18th of May.
Finals Week Schedule
• May 17, Monday - Periods 1-3
• May 18, Tuesday - Periods 4-6
• May 19, Wednesday - Periods 1-3
• May 20, Thursday - Periods 4-6
• No School Friday
*Students in a 0 or 7th period, see your 0 or 7th period teacher for finals information.
I want to thank you for supporting our school and most importantly for supporting your son/daughter.  Our students have accomplished a lot this school year. Although we were confronted with historical challenges beginning the year with distance learning, and now hybrid learning, our students and staff have given their best efforts to rise to the challenge.
We will have two sessions for summer school this year, one from June 8-30, 2021 and a second session from July 8-30, 2021.  I hope that your son or daughter is able to take advantage of the opportunities this summer. Please speak to your counselor to explore possibilities for summer classes ASAP!
When students return, Los Osos High School will have a new principal, Mr. Eric Cypher!  Mr. Cypher is a dynamic leader, who is also caring, compassionate and enthusiastic about becoming the next principal at LOHS. This is a home coming for Mr. Cypher as he is no stranger to LOHS having led our water polo program to multiple CIF Championships, was a dynamic teacher in the classroom and great leader as our Activities Director. After leaving LOHS to become an assistant principal for the last three year at Etiwanda High School, Mr. Cypher is very excited to return to Grizzly Nation and I know he will be an excellent principal at Osos!
Congratulations to the class of 2021, we are proud of you!
It has been a true honor and privilege to be your principal!  Have a great summer!
Claws Up!
Mr. Kirk