The University of California, Riverside, commonly known as UCR or UC Riverside, is a public research university and one of the ten general campuses of the University of California system. UCR is consistently ranked as one of the most ethnically and economically diverse universities in the United States. The main campus sits on 1,200 acres (486 ha) in a suburban district of Riverside, California, United States, with a branch campus of 20 acres (8 ha) in Palm Desert. Founded in 1907 as the UC Citrus Experiment Station, Riverside pioneered research in biological pest control and the use of growth regulators responsible for extending the citrus growing season in California from four to nine months. Some of the world's most important research collections on citrus diversity and entomology, as well as science fiction and photography, are located at Riverside.

UCR's undergraduate College of Letters and Science opened in 1954. The Regents of the University of California declared UCR a general campus of the system in 1959, and graduate students were admitted in 1961. To accommodate an enrollment of 21,000 students by 2015, more than $730 million has been invested in new construction projects since 1999. Plans are underway to open California's first new research-based public medical school in 40 years there by 2012.

The Washington Monthly ranked UCR 16th in the United States in terms of social mobility, research and community service, while US News and World Report ranked UCR's undergraduate program 94th in the nation (out of 368 colleges) based on peer assessment, student selectivity, financial resources, and other factors.U.S. News ranks UCR as the third most ethnically diverse and, by the number of undergraduates receiving Pell Grants (42 percent), the 15th most economically diverse student body in the nation. Nearly two-thirds of all UCR students graduate within six years without regard to economic disparity. UCR's extensive outreach and retention programs have contributed to its reputation as a "campus of choice" for minority students, including LGBT students. In 2005, UCR became the first public university campus in the nation to offer a gender-neutral housing option.

UCR's sports teams are known as the Highlanders and play in the Big West Conference of the National Collegiate Athletic Association (NCAA) Division I. Their nickname was inspired by the high altitude of the campus, which lies on the foothills of Box Springs Mountain. The UCR women's basketball team won back to back Big West championships in 2006 and 2007. In 2007, the men's baseball team won its first conference championship and advanced to the regionals for the second time since the university moved to Division I in 2001.