A procedure is demonstrated for constructing tables showing, for each score on a commercial reading achievement test, the percentage of real-world materials that the testee is likely to comprehend with at least a criterion level of proficiency, the percentages of students in a local or national sample who can competently comprehend a given percentage of materials, and which individuals or percentages of local and national samples have reached the state of being literate on the type of materials used to reference the test. Students are given a commercial reading test and some comprehensibility tests made from a sample of real-world reading tasks. The commercial test scores are regressed on the individual and mean comprehensibility test scores, and the regression equation is solved, fixing the comprehensibility score at the desired level of proficiency and varying the comprehensibility test mean to correspond to percentile points in the distribution of those means. The scores thus predicted are then used, along with the commercial test's norms, to construct the described tables. (Author/MH)