The purpose of this study was to determine the effect of explicitly differentiated reading instruction on eighth-grade students’ reading comprehension assessment scores and classroom reading grade scores in a rural middle school seeking to reestablish satisfactory No Child Left Behind, Adequate Yearly Progress, benchmarks.  After one school year of participation in assessment-based and readiness-focused explicitly differentiated instruction, randomly assigned students across all three reading ability conditions high (n = 25), middle (n = 25), and low (n = 25) had statistically significantly improved pretest-posttest reading comprehension assessment scores and classroom reading grade scores.  Furthermore, statistical equipoise was observed for posttest-posttest reading comprehension assessment scores and posttest-posttest reading grade scores where higher improve score frequencies and percents compared to lose score frequencies and percents were consistently observed.  While explicitly differentiated reading instruction prepared the majority of the study subjects for reading comprehension assessment improvement and classroom grade score improvement, students whose assessment scores and grade scores declined over time will require renewed initiatives. FULL MANUSCRIPT AVAILABLE AT: