This descriptive case study examined educators' perceptions of the effect of tiered instruction on the reading achievement of kindergarten students. The purpose was to explore and describe current cultural and structural conditions that support or inhibit effective school-level implementation of a Response to Intervention (RtI) model. This study was guided by the following research question: How do teachers perceive the effectiveness of a tiered instruction program in reading in full day kindergarten? Data was gathered from five educators and one administrator within a suburban public early childhood school through individual interviews, analysis of student benchmark assessments and a focus group discussion. Vygotsky's sociocultural theory, with its focus on interdependence among social and individual processes to construct knowledge, provided a lens through which to examine the context of the study and inform the findings. Findings from this study revealed understandings and beliefs that supported the use of tiered instruction as a general education model that benefitted all students, provided the necessary supports for beginning readers and contributed to reading success. Results indicated that communication, collaboration, shared goals, increased individual accountability, training and professional development contributed to the success and sustainability of tiered instruction. This study identified a number of components perceived to facilitate or challenge successful implementation of instructional practices, assessment and data-driven decision making within the RtI model. These findings have implications for educational practice and can be used to inform key stakeholders at the building and district levels. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]