This report presents the results of the National Assessment of Educational Progress (NAEP) long-term trend assessments in reading and mathematics, which were most recently given in the 2007-2008 school year to students at ages 9, 13, and 17. Nationally representative samples of over 26,000 public and private school students were assessed in each subject area. The most recent results are compared to those from 2004 and from the first year the assessment was conducted: the reading assessment was first administered in 1971, and the mathematics assessment was first administered in 1973. The long-term trend program has used essentially the same assessments in each administration year to provide data that can be used to evaluate changes in student performance over long periods of time. In 2004, a number of changes were made to the long-term trend assessment to update the assessment content and procedures while maintaining the ability to report trends over the long term. Some of the changes included replacing questions that were based on outdated contexts; changing some administration procedures; and providing accommodations for students with disabilities and for English language learners. These revisions did not alter the knowledge and skills that are assessed by the long-term trend assessments. In reading, average scores increased at all three ages since 2004. Average scores were 12 points higher than in 1971 for 9-year-olds and 4 points higher for 13-year-olds. The average reading score for 17-year-olds was not significantly different from that in 1971. In mathematics, average scores for 9- and 13-year-olds increased since 2004, while the average score for 17-year-olds did not change significantly. Average scores were 24 points higher than in 1973 for 9-year-olds and 15 points higher for 13-year-olds. The average mathematics score for 17-year-olds was not significantly different from that in 1973. (Contains 1 footnote, 21 figures and 9 tables.)