Purpose: The purpose of this quantitative quasi-experimental study was to focus on the difference of Instructional Reading Level (IRL) scores in Title I public elementary school students, before and after Tier II Response to Intervention (RTI) was implemented. Theoretical Framework: This study was applied theoretically to Vygotsky's sociocultural theory of cognitive development. Methodology: The specific aim of this quantitative study was to determine whether there was a significant difference and effectiveness (through the lens of public administration), when Tier II RTI was applied for the 2018-2019 school year to Title I public elementary school students as determined by their IRL scores. This study includes a secondary analysis of Title I public elementary school students' IRL scores from school district provided data. Findings: There was a significant difference in pre- and post-IRL scores, when Tier II RTI was provided to Title I public elementary school students. Title I public elementary school students who received Tier II RTI instruction for 6 consecutive traditional school months, scored 1 year higher on average, from their IRL pretest score to the IRL posttest score. Conclusions and Recommendations: Based on the researcher's current findings, Tier II RTI was found to be largely effective in Title I public elementary school students' IRL scores. Research can be expanded in the future by including Tier II RTI in Title I public elementary schools throughout the country to see if results can be replicated or even improved elsewhere. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]