To determine the relationship between particular reading materials used most frequently with students in grades one through six and the amount of progress students made during the 1982-83 school year, a study was conducted by the District of Columbia Public Schools. Nine of the ten reading materials on the approved textbook list were assessed, and 16,733 students, 42% of the students enrolled in grades one through six, who met the selection criteria were examined. The measure of student progress enlisted was keyed to reading progress. Data revealed that there was no significant difference in the amount of student progress associated with the nine tested texts, that the effectiveness of particular reading materials was not significantly influenced by the sex of the student, and that a particular material may be more effective or less effective at a given grade level depending on the instructional level of the student. (CRH)