This report deals with a variety of ways that have been, or could be, used to interpret the scales used in the National Assessment of Educational Progress (NAEP). Policymakers, researchers, and other users of assessment results need to understand the methods used for reporting NAEP. Having a reference is particularly important as the methods of reporting are changing. Chapter 1 covers the following methods that have been used, or could be used, to interpret scales: (1) percentage correct for each item; (2) average percentage correct; (3) item mapping; (4) scale anchoring; (5) achievement levels; (6) using scoring rubrics; and (7) benchmarking. The contrast between anchor levels and achievement levels is discussed. Chapter 2 discusses the distinction between norm-referenced and criterion-referenced interpretations, and the validity of the inferences drawn from NAEP interpretations. Issues of validity are especially important with regard to achievement levels, because they represent an effort to go beyond describing, to prescribing recommended levels of achievement for the nation. Eleven figures and four tables present analysis data. An appendix provides exemplar exercises for scale anchoring and for achievement levels. (SLD)