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. 
About Us Image
All CJUHSD students will graduate ready for college and careers.

Recent News

WeTip - Be the solution

WeTip

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

Upcoming Events

Board Meeting

Time: 5 PM – 8 PM
Location: Alta Loma High School

Board Meeting

Time: 5 PM – 8 PM
Location: Rancho Cucamonga High School

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
Grizzlies, 
 
Welcome back! Let’s kick off the second semester of the 2025–2026 school year with excitement, focus, and determination. We hope you enjoyed a restful Winter Break and are ready to jump back into learning, growing, and making the most of the months ahead. 
 
Seniors—this is your moment! Your final high school semester is officially underway. Stay focused, keep your eyes on the prize, and finish strong as you prepare to walk across the graduation stage. Your hard work, perseverance, and dedication will make this milestone truly unforgettable. Remember that Hard Work Pays Off! 
 
The start of a new year is the perfect time to reflect, recharge, and refocus. I encourage each of you to think about your successes and challenges from last semester and set new academic and personal goals for 2026. Let’s use this opportunity to reset, strengthen positive habits, and continue building the skills that will set you up for success—now and in the future. 
 
As we launch into this new semester, we also recognize there will be some important adjustments—particularly with the implementation of our new Cell Phone Policy, which aligns with state expectations. Our success depends on consistency, communication, and partnership between school and home. Students are expected to follow clear cell phone expectations, including proper phone placement during instructional time and no phone use during instruction, including restroom use. The continued and consistent use of the 5Star App will support our No Cell Bell-to-Bell policy and help reinforce accountability. We appreciate your cooperation and support as we work together to create a focused, distraction-free learning environment for all students. 
 
To support students in reaching their goals, we have many resources available: 

   - Before and After School Tutoring: Extra help when you need it 
   - 4G Saturday School: A great opportunity to catch up or get ahead 
   - Canvas: Stay organized and on top of assignments 
   - Counselors and Teachers: Your biggest supporters—always here to guide and encourage you 
 
Mark your calendars! School will not be in session on the following dates: 

   - January 19, 2026 – Martin Luther King Jr. Day 
   - February 9, 2026 – Lincoln’s Birthday 
   - February 16, 2026 – Presidents Day 
   - March 30 – April 3, 2026 – Spring Break 
 
Grizzlies, let’s make this semester one to remember. Keep Working hard, Inspire each other, Lead with integrity, and Dream big. Together, we will continue to strengthen our campus community and achieve incredible things. 
 
Keep those Claws Up, Grizzlies and stay WILD! 
 
Eric Cypher 
Principal  
Los Osos High School