The purpose of this study was to investigate teachers' and administrators' perceptions of the implementation and effectiveness of Response to Intervention (RTI) strategies in their schools. The study used a mixed-methods research design. Data were collected through multiple-choice and open-ended surveys administered to elementary English language arts general education teachers, special education teachers in Kindergarten through fifth grade, and administrators in seven elementary schools. Quantitative data were analyzed using the Mann-Whitney U and Kruskal-Wallis Analysis of Variance of Ranks. Qualitative data were analyzed by the researcher to determine similarities and differences among the written responses. All data were gathered during the 2011-2012 school year. Teachers' responses were divided into two groups: (1) general education teachers, and (2) special education teachers. Administrator data were analyzed as a separate group. The findings of the study showed that there was no statistically significant difference in teachers' and administrators' perceptions regarding the effectiveness of RTI interventions in increasing student achievement, the depth of implementation and level of rigor used to incorporate RTI into instruction, the value of teacher collaboration in implementing RTI, and the validity of RTI in determining possible candidates for special education services. There was a statistically significant difference in teachers' and administrators' perceptions as to the amount of time required to incorporate RTI into their instructional time; special education teachers stated that they would like to have more time in RTI interventions. Participants provided additional insight into their answers by providing explication of their perspectives. [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.]