The authors investigated whether the curricular structure of an economics course (semester, trimester, or compressed block schedule) has an effect on an undergraduate's subsequent retention of course material, while controlling for other relevant differences. They tested separately for theoretical or process comprehension and for graphical construction or interpretation, while separating microeconomics from macroeconomics content as well. They used an instrument to address the no-stakes testing problem, and their Heckman two-stage estimations present some interesting results for educators and institutional policymakers alike. (Contains 2 tables.)