The National Assessment of Educational Progress has now completed two major assessments of reading. The first took place in the 1970-71 school year, the second during the 1974-75 school year. Both assessed the achievement of students aged nine, thirteen, and seventeen. This report focuses on the results of these two assessments, comparing changes in observed performance and discussing technical problems encountered in interpreting the changes. Among the findings were that nine-year-olds during the second assessment read better than nine-year-olds four years earlier; that thirteen- and seventeen-year-olds improved slightly in literal comprehension but declined in inferential comprehension; that black nine-year-olds and students from the southeast improved more than did students in the nation as a whole; and that girls continued to read better than boys at all age levels. Results are reported separately for each set of skills at each age level. Appendixes discuss problems in interpreting change data, estimated population of reporting categories, and average group differences. (AA) Primary type of information provided by report: Results (Change) (Technical Summary).