The study described in this report included 128 high school economics teachers from 106 schools in Arizona and California, half of whom were randomly assigned to the "Problem Based Economics Instruction" condition and half of whom were randomly assigned to the comparison condition. High levels of teacher attrition occurred after randomization and before implementation. The analysis sample included 64 teachers, with 35 in the treatment condition and 29 in the comparison condition. Student attrition was low, and the student analytic sample was shown to be equivalent in economic literacy at baseline. Intervention teachers used "Problem Based Economics Instruction" materials as a major portion of their curriculum content and instructional program during the 2007-08 academic year, whereas comparison teachers used their schools' standard instructional materials. The study assessed the effectiveness of "Problem Based Economics Instruction" by comparing the economics knowledge of students in the treatment and comparison groups at the end of their implementation semester. The study found no statistically significant difference on the economics knowledge of students in grades 11 and 12 in the classes that used "Problem Based Economics Instruction," relative to students in the comparison classes. However, the effect size of 0.29 for the economics knowledge domain was positive and large enough to be considered substantively important according to the What Works Clearinghouse (WWC) criteria (that is, at least 0.25 standard deviations). The research described in this report meets WWC evidence standards with reservations. Appended are: (1) Study details; (2) Outcome measures for the economics knowledge domain; and (3) Study findings for the economics knowledge domain. A glossary of terms is included. (Contains 7 endnotes.) [The following study is the focus of this "Quick Review": "Effects of Problem Based Economics on High School Economics Instruction. Final Report. NCEE 2010-4002rev" (ED533126).]