The purpose of this article is to report on the development and initial use of a pesticide knowledge test (PKT) specifically designed to evaluate agricultural workers' knowledge of the content mandated by the federal Worker Protection Standard (WPS). The PKT is a 20-item, true-false test, used in a sample of 414 adult and adolescent migrant farmworkers in Oregon. The overall mean score, i.e., number correct, was 15.67(78.4%), with both adults and adolescents demonstrating the most difficulty with questions related to the overall health effects of pesticides. The internal consistency was 0.73, when estimated using a method to correct for small sample sizes. Only six items had less than 70% correct answers. Content validity was achieved by basing the items directly on the Worker Protection Standard; face validity was obtained by having the final version of the test reviewed by a bilingual (English-Spanish) educator familiar with the requirements of the WPS. Overall, adult participants scored better than adolescents, and those with previous pesticide training scored better than those without. There were no differences in scores based on gender or whether the test was taken in English or Spanish; however, participants who spoke indigenous languages scored significantly lower than those who did not. These results indicate that the PKT is a valid, reliable measure of worker knowledge of the content of the WPS, although it does not measure the extent to which that knowledge is actually used in the work setting.