This was a quasi-experimental comparison study conducted in a rural suburban school district in Texas. The primary purpose of this study was to determine whether elementary students with dyslexic tendencies, who received the Tier III, Orton-Gillingham- (O-G) based Take Flight reading intervention being piloted on two campuses, showed statistically significant greater reading growth than the comparison control students who received the existing district-created reading intervention on two other campuses. The district created the comparison control reading intervention by integrating four commercial programs--the Tier II program; the Orton-Gillingham-based Rite Flight Rate and Rite Flight Comprehension program; Systematic Instruction in Phonological Awareness, Phonics, and Sight Words; and the Leveled Literacy Intervention program. The data used for this study were those already collected by the district for the 2014-2015 and 2015-2016 school years. The Developmental Reading Assessment Second Edition (DRA2) and the State of Texas Assessment of Academic Readiness (STAAR) reading assessments were the instrumentations used to collect the data. A secondary purpose of this study was to compare the reading growth of the students in this study who received the experimental Take Flight intervention and the comparison Rite Flight intervention to the reading growth of the general population of elementary students in this district, and determine whether the interventions made positive gains in closing the reading achievement gap. A third purpose was to determine the cost benefit per student of the experimental Take Flight reading intervention compared to the Rite Flight intervention. The findings indicated no statistically significant difference in the effectiveness of the two reading interventions (DRA2 or the STARR). However, although the effectiveness was not statistically significant due to the small sample size, Rite Flight appears to have been more effective at accelerating text levels and meeting the standard on the STAAR. The general student population started out higher and ended higher on the DRA2 than the students receiving either reading intervention. The general student population also had a higher DRA2 text level mean and a higher STAAR mean than either intervention group. In addition, Rite Flight was more cost effective. [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.]