The authors of this article estimate the learning effects of the flipped classroom format using data from 16 sections of principles of microeconomics over a 4-year period. The experimental design is unique in that two treatment and two control sections were taught during the fall semester in four consecutive years. Further, the instructor switched the time of day when the treatment and control sections were taught each year. Controlling for gender, ACT score, a normed high school GPA, Pell Grant award, time of day, and initial knowledge of economics, the authors find no evidence of increased learning using end-of-semester measures for students in the flipped classroom in comparison to sections with a moderate amount of active learning.