NAEP achievement levels are “performance standards that describe what students should know and be able to do. Results are reported as percentages of students performing at or above three NAEP achievement levels (NAEP Basic, NAEP Proficient, and NAEP Advanced). Students performing at or above the NAEP Proficient level on NAEP assessments demonstrate solid academic performance and competency over challenging subject matter. It should be noted that the NAEP Proficient achievement level does not represent grade level proficiency as determined by other assessment standards (e.g., state or district assessments).”