In an attempt to measure the effect that dialect of presentation has on Black-English-speaking children's oral reading performance, this study measured the percentage of unknown words attempted by third and fifth grade subjects on equivalent forms of an oral reading task presented in Standard English, Black English standard orthography, and Black English nonstandard orthography. Results indicated that, overall, while subjects scored similar percentages of omissions on the Standard English and Black English standard orthography forms of the oral reading task, fifth graders scored a smaller percentage of omissions on the Black English standard orthography form of the oral reading task, and third graders scored a smaller percentage of omissions on the Standard English form. All subjects scored a higher percentage of omissions on the Black English nonstandard orthography form of the oral reading task than on the other two forms. Educational implications are discussed. (Author)