The nature and extent of errors in the oral language of pupils in elementary and secondary school years was investigated. One hundred and eighty subjects were selected from public schools and were administered the Experimental Form B of the new Gray Oral Reading Test. Obtained data were analyzed with descriptive techniques and tests of statistical significance. It was found that (1) oral reading errors that decreased as grade level increases were repetition, no response, and inversion; (2) errors that increased as grade level increases were partial mispronunciation and gross mispronunciation; (3) errors that persisted throughout the grades were substitution, omission, and insertion; and (4) errors that appear in the same proportionate frequency whether pupil read passages of difficulty below or above their own level were substitution, insertion, and no response. Three other observations were that (1) chronological maturity accompanies reduction in total oral reading errors, (2) sex differences are negligible in this study, and (3) the reduction rate of total oral reading errors is rapid during the primary grades and slower and irregular through the secondary levels. (AW)