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

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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: Chaffey High School

Board Meeting

Time: 5 PM – 8 PM
Location: Ontario 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
Los Osos High School Grizzlies, Students, Parents, and Families, 
 
The 2025–26 school year is off to a strong start, and the first quarter is already flying by! Thanks to the dedication of our staff, student leaders, and parent volunteers, we are excited for what lies ahead and remain committed to preparing every student for success on the road before them. 
 
At Los Osos, we provide a wide range of academic supports to ensure our students have the tools they need to thrive. These efforts are rooted in our schoolwide vision: “All students at Los Osos will graduate ready for college and career.” Strengthening college readiness through increased A-G completion and reduced freshman failure rates continues to guide our academic goals. Enhancing classroom instruction, expanding tutoring opportunities, and offering targeted support programs remain top priorities. In addition, our Peer Counseling and Reach Out programs provide essential resources to support mental health and wellness, helping students achieve balance and success both inside and outside the classroom. 
 
Beyond academics, extracurricular involvement is a cornerstone of the Los Osos experience. Our school offers an impressive variety of Visual and Performing Arts programs, clubs, sports teams, and student organizations to match every interest. Whether through the Gardening Club’s hands-on projects, our award-winning robotics team, nationally recognized FBLA and Speech & Debate programs, or countless other opportunities, Grizzlies have countless ways to discover passions, build skills, and form lasting connections. These activities not only enrich the high school experience but also foster leadership and a strong sense of community. 
 
As we continue into this school year, I want to remind our Grizzlies that Hard Work Pays Off! Our staff is devoted to guiding you toward your dreams, but success begins with you. It starts with embracing the Grizzly mindset: taking ownership of your learning, showing resilience during challenges, and seeking help when needed. I challenge every Grizzly to attend school daily and on time, complete all assignments, and strive to earn a C or higher in every class. These habits will prepare you for the opportunities of college, career, and beyond. 
 
Parents, your partnership with us is vital. I encourage you to emphasize the importance of daily attendance, stay connected with teachers, and consistently monitor your student’s progress through Canvas. Please also be sure you have set up and are using ParentSquare to receive timely communication from our school. Together, we form the strong foundation that ensures every student’s success. For additional guidance, I invite you to visit the Parent Resources tab on our school website. 
 
Los Osos High School is an amazing place to learn, grow, and lead. We look forward to working alongside you for another remarkable school year! 
 
Claws Up and Stay W.I.L.D! 
 
Eric Cypher 
Principal of Los Osos High School