The school was established in Ontario, California in 1883, when city founders and brothers George and William Chaffey donated land and established an endowment for a private college. The private school was founded as the Chaffey College of Agriculture of the University of Southern California; USC, also a private university, had been founded three years earlier in nearby Los Angeles. The cornerstone of the new school was laid on March 17, 1883 at Fourth and Euclid in Ontario; it opened on October 15, 1885. The original institution included a secondary school and was run by USC until 1901. During this period, Chaffey’s football team had a 1-1 series with the young USC football team, winning 32-6 in 1893 and losing 38-0 in 1897.
Financial troubles forced the school to close in 1901. The building was taken over by the city and became the home of Ontario High School (now Chaffey High School). In 1906 the Chaffey endowment was legally separated from USC and reorganized to benefit the newly created Chaffey Union High School District. When Ontario High school opened to students from Upland in 1911, its present name was adopted. In 1916, the Chaffey Junior College of Agriculture was added as a postgraduate department to the high school. The school’s buildings were renovated and additional buildings added during the New Deal.
A separate junior college district was created in 1922 and in 1957 bonds were approved in support of a complete separation of the high school and college facilities. The current location in Alta Loma opened in the spring of 1960.
The Measure L bond provides up to $230 million in bonds during a 10-year period for the Facilities Master Plan. Off-site campuses in Fontana and Chino are also part of this master plan, with new Fontana buildings and a new Chino campus being developed. The college remains open while undergoing construction, except for occasional diversions in traffic and parking.