A sample of 96 ninth-grade vocational agriculture students in 21 Illinois high schools participated in a study of the relationship between socioeconomic status and reading comprehension. An instructional unit was tested for reading level and rewritten at an easier level. Students were classified by socioeconomic class and randomly assigned to experimental and control groups. They read either the original or rewritten version and responded to a 30-item criterion test to measure comprehension, and to Test Six of the Iowa Test of Educational Development. Of three socioeconomic groups, the middle group showed significantly better understanding of principles in the material. Students who read rewritten materials scored higher, but no differences were found between experimental and control groups or between socioeconomic groups on recall. No differences were found between experimental and control or between socioeconomic groups in reading comprehension, as measured by the Iowa Test of EDucational Development. This Ed.D. thesis was submitted to the University of Illinois. (JM)