Although there is a large body of research on effective early reading instructional practices, schools continue to implement instruction and intervention that is not aligned to the science. Over the past 25 years, a Multi-Tiered System of Supports (MTSS) framework has emerged as a leading framework for advancing the reading skill development of all students. However, little is known about which aspects/components of its implementation are required to advance students' reading outcomes. This study utilized multiple regression examine the degree to which aspects/components of MTSS implementation (universal screening, explicit/direct instruction, consistency in tier 1 instruction, and individualized instruction in tier 2 interventions) predict students' early reading performance as measured by benchmark attainment on DIBELS Nonsense Word Fluency and Oral Reading Fluency. Predictors and dependent measures were coded at the grade level for 53 schools, with a total of 166 cases representing each grade level across participating schools. Results indicated that consistency in the implementation of foundational tier 1 reading skill instruction, as well as the use of skill-focused grouping for tier 2 intervention, were predictive of student reading success. Although research supports the value of skill-focused CBM universal screening assessments and providing explicit, direct reading instruction, neither screening assessment use nor the provision of explicit and direct instruction were found to be a significant predictor of student reading success. Study limitations that may explain the lack of significant findings for these latter predictors, along with recommendations for future research, are discussed. [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.]