The authors extend the literature on the efficacy of high school economics instruction in two directions. First, they assess how much economic knowledge that California students acquired in their compulsory high school course is retained on their entering college. Second, using as a control group some college students from the state of Washington, where there is no mandate for high school economics instruction, the authors evaluate the impact of California's high school economics mandate on students' economic literacy when they enter college. The testing instrument is the "Test of Economic Literacy" (TEL). (Contains 3 tables and 9 notes.)