One hundred fifty-one urban ninth grade students participated in an investigation of the effect of differentiated content in two congruent tests of reading. A congruent test was constructed by substituting information relevant to junior high school students within the parameters of a nonrelevant, standardized state test of reading. By maintaining identical format, grammatical structure, flow of thought, patterning of questioning, and readability level, the two tests were shown to be of equivalent difficulty. Comparison of subscores of boys and girls, blacks and whites, as well as eight individual classes showed that there was a general tendency toward greater achievement on relevant reading content, with no one group significantly exceeding another statistically. Other results indicated that the content of the standardized state reading test is basically alien to a number of urban children and may penalize them unfairly, and that a number of apparently noncompetent readers in junior high school may actually possess minimal reading ability within the framework of their experiential background. (Tabular material is included, and sample test questions, word lists, raw scores, and a list of interest clarifying questions are appended.) (AEA)