MTSS promises a school-wide early warning system, high-quality instruction, and evidence-based interventions. However, research has focused mainly on the elementary level. This study examined the beliefs and perceptions of over 300 administrators and teachers currently implementing MTSS in secondary schools using survey research. Results showed that special education teachers and administrators had significantly higher MTSS/RtI beliefs and perceptions of their own academic and behavioral MTSS/RtI instructional and intervention skills. Recommendations include the need for extensive and intensive professional development, delineation of role clarity, increased fidelity of implementation, and staff accountability.