Although the University of California, Berkeley has increased efforts to involve undergraduates in scientific research, little data exists regarding the number of undergraduate researchers. The University of California Undergraduate Experience Survey (UCUES) presents an opportunity to investigate the extent of undergraduate research involvement at the UC Berkeley. The data (N=5,347) show that the frequency of student participation in research under the direction of a faculty mentor varies significantly based on whether students are receiving course credit, pay, or working as a volunteer. Undergraduate research participation also varies between STEM majors and social science or humanities majors (non-STEM), with slightly more STEM majors participating. The data show that women are participating in STEM research opportunities at a lower rate than men but participating in non-STEM research opportunities at a higher rate than men. The data also show that Asian, Filipino, and Pacific Islanders (AFP students) account for 50% of all undergraduate researchers in STEM fields and 35% of all non-STEM researchers. However, the data also reveal that African American, Chicano-Latino, AFP, White, American Indian, and international students are all participating at almost the exact same rate in undergraduate research (between 24% and 27% by ethnic or racial category). Further analysis regarding the relationship between undergraduate research experience and the highest parental education level reached, as well as high school grade-point average and standardized test scores (SAT I and ACT) is presented. Implications for higher education administrators, education researchers, faculty mentors, and undergraduate students are discussed.