This article reports the results of a study of Canadian students at the University of Western Ontario, which focuses on the importance of economics courses for high school students in Canada. The main findings are that, adjusting for other factors, students who had taken previous economics courses did not begin their principles course with significantly more knowledge, nor did they learn significantly more during the semester. Poorly trained teachers, insufficient time spent on complex and confusing issues, and insufficient grounding in related subjects may result in little learning, or even worse, greater confusion among students who take high school economics courses than among similar students who do not. Women did slightly but not significantly worse than men, and students with no calculus did virtually as well as students with that background. Results are not consistent with the hypothesis that high school economics courses simply concentrate on consumer economics, bookkeeping, or current events.