This ex post facto descriptive-comparative quantitative study compared the differences in reading achievement between groups of 6th- through 8th-grade students enrolled in a response to intervention (RtI) classroom against groups of students enrolled in a general education classroom. Students across English language learner and low socioeconomic status subgroups who were identified as at-risk by their performance on the previous school year's 4th-quarter grade-level benchmark assessment, as well as the current year's Arizona's Instrument to Measure Standards scores, and were not labeled as special education students, were given instruction and intervention in an RtI classroom. Quarterly benchmark assessments, reading-level-grade equivalent scores as measured by the Accelerated Reader program and Arizona's Instrument to Measure Standards test, were used to ascertain student growth measures. The population included 1,831 6th-through 8th-grade students with 201 of those enrolled in a language arts RtI classroom in a Central Arizona school district's K-8 school during the 2009-2010 school year. The results of this study indicated that the students who participated in the RtI classroom model did not have statistically significant improvements in their reading achievement during the years of enrollment in the program compared to students who were enrolled in a general education classroom. This research implies that RtI in the middle grades poses challenges not seen at the elementary level. The complexity of content area texts, student motivation, and school-wide systems contribute to the success of an RtI initiative. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]