The Nation's Report Card[TM] informs the public about the academic achievement of elementary and secondary students in the United States. Report cards communicate the findings of the National Assessment of Educational Progress (NAEP), a continuing and nationally representative measure of achievement in various subjects over time. The National Assessment of Educational Progress (NAEP) U.S. history assessment evaluates students' understanding of the development of America's democratic institutions and ideals. Students demonstrated their knowledge of democracy, culture, technological and economic change, and America's changing world role. A nationally representative sample of 29,000 students at grades 4, 8, and 12 was assessed in 2006. This report compares 2006 student performance to similar assessments conducted in 1994 and 2001, and finds that America's twelfth-, eighth-, and especially fourth-graders know more U.S. history now than in the past. This report includes the results and assessment content of the NAEP. (Contains 6 tables and 16 figures.)