This study used a convergent mixed-method design and a pragmatic approach to examine how professional development (PD) affected teachers' confidence in their abilities to use the Multi-Tiered Systems of Support (MTSS) framework in a rural Mississippi middle school. Grounded in Bandura's self-efficacy theory, the study aimed to answer two research questions: (1) How does professional development influence teachers' confidence in implementing MTSS? and (2) What practical challenges do teachers face when applying MTSS in real-world educational settings? Data were gathered using the MTSS Instructional Survey and the MTSS Leadership Survey from 19 participants, four instructional leaders, and 15 teachers via Qualtrics. Quantitative data were analyzed utilizing SPSS, while the qualitative data from open-ended research questions were examined using NVivo. The pragmatic approach of the study prioritized practical solutions to implement MTSS by combining data with teachers' perceptions. Quantitative analysis showed a positive relationship between professional development (PD) hours and the Multi-Tiered System of Support (MTSS) fidelity. Interventionists achieved the highest fidelity score at 92%, while assistant principals achieved the lowest at 80%. Qualitative analysis revealed challenges such as resource limitations, time constraints, and teacher burnout, which hindered full implementation despite increased self-efficacy from PD. This mixed-method approach provided a balanced exploration of empirical data and real-world challenges, emphasizing the importance of targeted professional development and structural changes in rural schools. The findings have significant implications for supporting educators, improving teacher performance, and promoting academic equity in rural Mississippi schools. [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.]