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 2006 NAEP civics assessment evaluated students' understanding of the democratic institutions and ideals necessary to become informed citizens in shaping America's future. Students demonstrated this knowledge in areas deemed important for citizenship in our constitutional democracy. A nationally representative sample of more than 25,000 students at grades 4, 8, and 12 was assessed in 2006. The results are compared with those of the 1998 civics assessment, and find that average scores improved from 1998 to 2006 only at grade 4, mostly among lower-performing students. This report includes the results and content of the NAEP. (Contains 4 tables and 8 figures.)