The authors examined the effects of remedial mathematics on performance in university-level economics courses using a natural experiment. They studied exam results prior and subsequent to the implementation of a remedial mathematics course that was compulsory for a subset of students and unavailable for the others, controlling for background variables. They found that, consistent with previous studies, the level of and performance in secondary school mathematics have strong predictive power on students' performances at university-level economics. However, they found relatively little evidence for a positive effect of remedial mathematics on student performance. (Contains 21 notes, 5 tables and 4 figures.)