The purpose of this National Assessment of Educational Progress (NAEP) Achievement Levels Validity Argument Report is to synthesize evidence currently available to address the validity of the interpretations and uses of the NAEP Achievement Levels. Validity is the extent to which theory and evidence supports or refutes proposed and enacted test score interpretations and uses. This report was conceptualized as one of many activities outlined in an Achievement Levels Work Plan in response to recommendations made by the National Academies of Sciences, Engineering, and Medicine (NASEM) in their independent evaluation of the NAEP Achievement Levels (NASEM, 2017). This report touches on all NAEP subject areas but is primarily focused on the achievement levels associated with reading and mathematics because these subjects were the focus of NASEM's evaluation and are the most frequently assessed subject areas for NAEP. This report outlines accumulated validity evidence that can be used to clarify the appropriate uses and interpretations supported by that evidence, noting common inappropriate uses and interpretations not supported by evidence.