The National Assessment Governing Board has a legislatively mandated responsibility to develop National Assessment of Educational Progress (NAEP) achievement levels. The Board Policy Statement on Developing Student Achievement Levels for the National Assessment of Educational Progress provides policy definitions of "NAEP Basic," "NAEP Proficient," and "NAEP Advanced" -- and describes the principles for setting achievement levels. The policy definitions are general, high-level expectations of what students should know and be able to do and consistent across all NAEP assessments. Content achievement level descriptions (ALDs) are specific descriptions of what students at each level should know and be able to do for each individual assessment as specified in the frameworks. The National Assessment Governing Board contracted with Pearson to design and implement a review of the achievement level descriptions (ALDs) for NAEP Reading and Mathematics assessments for grades 4, 8, and 12. This document describes the procedural and technical aspects and outcomes of the operational ALD Review study. In particular, this report addresses the Board's updated achievement levels policy that called for the development of Reporting ALDs to state how the assessment content (defined by the Reporting ALDs) aligns with the existing content ALDs and achievement level policy definitions.