Some oral reading errors were found to be more significant than others in evaluating a pupil's performance in reading at six comprehension levels. The percentage of seven kinds of errors (pronunciation, mispronunciation, omission, substitution, addition, repetition, and punctuation) was computed to the levels of reading comprehension for good, average, and poor readers. Thirty fourth-grade students were divided into these three groups based on their stanine scores on the Word Meaning and Paragraph Meaning subtests of the Stanford Achievement Test. Each subject was then administered individually oral readings and questions from the Standard Reading Inventory until six reading comprehension levels were obtained for each subject. Results showed (1) a significant difference among the means of the six comprehension levels with respect to eerors in pronunciation, mispronunciation, omission, substitution, and repetition; (2) significant differences among good, average, and poor readers with respect to errors in pronunciation, substitution, repetition, and omission; and (3) significant differences in the shape of the curves defined over the six comprehension levels for the three groups of readers with respect to errors in pronunciation and substitution. Tables and references are included. (VJ)