Since 1992, NAEP results have been reported in relation to three achievement levels: basic, proficient, and advanced. However, the use of achievement levels has provoked controversy and disagreement, and evaluators have identified numerous concerns. This publication evaluates the NAEP student achievement levels in reading and mathematics in grades 4, 8, and 12 to determine whether the achievement levels are reasonable, reliable, valid, and informative to the public, and recommends ways that the setting and use of achievement levels can be improved.