In this qualitative case study the researcher examined educators' perceptions of an RTI/MTSS model of instruction and how staff perceptions relate to fidelity of implementation. The purpose of this research was to investigate educators' understanding of the critical components necessary to support implementation of RTI/MTSS framework. The overarching research question guiding this study was: How do grade two team members, support staff and the building administrator in one Massachusetts elementary school perceive the process, structures, fidelity of implementation and impact of an RTI/MTSS model? Sub-questions illuminated factors that facilitated or hindered the implementation process of an RTI/MTSS model. Data was gathered from student assessments, individual interviews, self-report surveys and a focus group discussion.Participants in this study include three grade two teachers, a special educator, a psychologist, a literacy coach and the building administrator. Vygotsky's sociocultural theory, which focuses on socially mediated activities to support learning and development, provided a lens through which to examine the circumstances of the study and inform the findings. Study findings revealed educators understood and embraced RTI/MTSS as a general education initiative that allowed educators to personalize instruction and reduce the number of special education referrals. Results indicated that multiple tiers, assessment, data informed decision making, collaboration, and shared accountability contribute to successful implementation of the RTI/MTSS model. Lack of resources, inadequate planning time, unscheduled additional tiers of instruction, and insufficient trainings challenge implementation. These findings have implications for educational practice and will inform key district stakeholders with the information and data necessary to sustain the RTI/MTSS framework.