The primary purpose of this study is to assess student-level impacts of a problem-based instructional approach to high school economics. The curriculum approach examined here was designed to increase class participation and content knowledge for high school students who are learning economics. This study tests the effectiveness of Problem Based Economics, developed by the Buck Institute for Education, on student learning of economics content and problem-solving skills. Student achievement outcomes are of primary importance and are hypothesized to be mediated by changes in teacher knowledge and pedagogical practice. This study targeted high schools in both urban and rural areas and engaged teachers who committed to teach economics during the 2007/08 academic year. The study was implemented from summer 2007 through spring 2008 in high schools in Arizona and California. The findings of this study confirm that students benefited from the combination of the professional development program, ongoing support for teachers, and the Problem Based Economics curriculum. At the same time, teachers reported satisfaction with the Problem Based Economics materials. Teachers in the sample had, on average, fewer than three college-level economics courses; the opportunity to engage in a five-day workshop in economics instruction offers support to teachers who are interested in advancing their own professional development and increasing content knowledge. (Contains 1 table.) [For related report, "Effects of Problem Based Economics on High School Economics Instruction. Final Report. NCEE 2010-4002," see ED511228.]