Context: The prevalence of sexually transmitted diseases and associated risk behaviors among California farmworkers is not well described. Purpose: To estimate the prevalence of sexually transmitted diseases (STDs) and associated risk behaviors among California farmworkers. Methods: Cross-sectional analysis of population-based survey data from 6 California agricultural regions was performed for participants tested for Chlamydia trachomatis (CT), Neisseria gonorrhea (GC), and syphilis, and who completed an interviewer-administered behavioral risk factor survey. Findings: Among the 403 males and 234 females examined and interviewed, males (29.3%) were more likely than females (9.6%) to have had 2 or more sex partners in the past 5 years. Forty-two percent of males ever had sex with a commercial sex worker; unmarried males were more likely than married males to report sex with a commercial sex worker in the past 2 years. Twelve percent of males and 5% of females reported ever having had an STD. Most participants did not report any methods to protect against STDs. Of 192 males and 178 females tested for CT, 3 males and no females were positive. No cases of GC were found. Of 387 males and 194 females tested for syphilis, 4 males and 1 female had positive rapid plasma reagin (RPR) and Treponema pallidum particle agglutination (TPPA) results. Conclusions: In this population-based survey among agricultural workers, there was low STD prevalence but high prevalence of sexual risk behaviors, particularly among males.