This study is an assessment of economic knowledge among students who receive formal economic instruction in their senior year of high school. Our sample was drawn from seven high schools in two large school districts in Orange County, California. Students were enrolled in the compulsory, semester-long economics course, a state requirement for high school graduation. Our key performance measure is the Test of Economic Literacy (TEL). Using a pretest–post-test design, we find that initial knowledge of economics is not strong among the students. After one semester of formal economics instruction, TEL examination scores improve by 12.3 percentage points on average.