This study consisted of a mixed-methods comparative analysis of the implementation of the Multi-Tiered Systems of Support (MTSS) in public school districts in the state of Missouri. The researcher surveyed nine public school districts similar in demographics of socio-economic representation, free and reduced lunch percentage, and average daily fund expended to educate students. One district administrator responsible for the implementation of MTSS represented each school district. In the qualitative component of the study, the researcher utilized an original electronic survey to gather insights into the unique implementation path each district employed. Coding and analysis resulted in identification of themes, similarities, and differences. The researcher interviewed 2 state-level leaders integral in the design and implementation recommendations from a state-level perspective. Coding and analysis of interview responses resulted in identification of similarities and differences in state and district-level implementation of MTSS. The quantitative component of study included collection and analysis of secondary data obtained from the Missouri Department of Elementary and Secondary Education via the Missouri Comprehensive Data System. The researcher obtained and analyzed elementary achievement and student attendance data to determine a difference within districts with full and partial implementation of MTSS. Through analysis of the qualitative surveys and interviews, the researcher found unique implementation paths among the study districts. All nine study districts implemented differently and none utilized a recommended path or blueprint. District implementations varied from perceptions held among the state-level leaders interviewed. Through analysis of the quantitative component of the study, the researcher identified no difference in achievement and student attendance in districts deemed full implementation in comparison to partial implementation. The researcher recommended continued attention to successful implementation of MTSS at state and district levels. Future attention with focus on increased technical support and funding at the state level held the promise of prompt, appropriate supports to students who struggle in the academic, behavioral, and social skill areas. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]