This transcendental phenomenological study, grounded in Bandura's self-efficacy theory (1997), investigates K-4 specialized literacy professionals' (SLPs) experiences and perceptions of implementing Response to Intervention (RTI) within a Multi-Tiered System of Support (MTSS) framework. Data collected from interviews and self-reported journal entries of nine "academic instructional specialists" provide a comprehensive understanding of their roles, responsibilities, experiences, and the factors that shape their self-efficacy in elementary education. The findings highlight the critical role that specialized literacy professionals fulfill in meeting the diverse needs of students through evidence-based, systematic interventions. Their responsibilities extend beyond direct instruction to encompass continuous assessment, progress monitoring, and adapting instructional strategies grounded in empirical evidence. Such an approach highlights the importance of collaborative efforts for successfully implementing RTI within a continuously changing educational environment. The study also reveals challenges specialized literacy professionals face, such as increased workload, the necessity for role adaptation, and a lack of sufficient support, all of which affect their self-efficacy. Despite these obstacles, specialized literacy professionals exhibit resilience attributed to collaborative networks, professional development opportunities, and the positive outcomes of their intervention efforts. The research emphasizes the significance of adaptability and continuous learning in improving specialized literacy professionals' effectiveness within the RTI-MTSS framework. It shows how these attributes significantly enhance SLPs' ability to implement effective interventions, adjust to the evolving educational landscape, and meet the varied needs of students. The study presents implications for practice and policy and recommendations for future research. [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.]