Purpose: The purpose of this study is to investigate the effect of frequent testing on the performance of undergraduate freshmen. Methodology: The impact evaluation of the intervention is designed as a field experiment -a randomized control trial. First, instructor divided the class in groups of three students in a joint-liability framework, a setting that fosters peer monitoring among students. Then, the groups were randomly assigned to high-frequency testing (tests on a weekly schedule) or a low-frequency testing (tests on a biweekly schedule). Each testing condition lasted for 15 weeks, and data on academic achievement were collected both before and after the intervention. Findings: Although high-frequency groups show a higher mean performance on academic results, the findings do not indicate a definitive improvement in performance in weekly versus biweekly testing. We related our findings with recent discoveries on students’ perception of frequent assessments and its relation to motivation. Originality: A large body of educational literature investigates the effect of the frequency of testing on learning performance. Less attention has been devoted to explore the mechanisms behind that relationship. We contribute to this emerging literature analyzing the effect of test frequency on a sample of Uruguayan university students, in a novel setting (a joint-liability framework), exploring mechanisms and suggesting lessons for future research.