This study aimed to determine the impact of the Math Matters Program on student achievement in third- and fourth-grade math and to understand leaders' perceptions of the Math Matters Program. Researchers analyzed end-of-year or spring Northwest Evaluation Association and Measures of Academic Preparation math results across treatment and control groups to determine the impact of the Math Matters Program, including Common Core-aligned resources, instructional coaching components, and professional development. Additionally, researchers analyzed the Math Matters Program interim assessment data across schools within the Math Matters Program to understand if there was a difference in student achievement among treatment schools to better understand the impact, if any, of the Math Matters Program. Leader perception was analyzed by reviewing the results from the Performance Ready Leader Questionnaire among various treatment schools. In analyzing the Performance Ready Leader Questionnaire data, researchers aimed to understand if the perception of the program varied based on experience with the program or if the perception was impacted by the race of the school leader participating in the program. This mixed-methods study revealed a statistically significant difference between treatment and control schools; the control schools produced higher student achievement. In addition, there was no statistical difference in Math Matters Program interim assessment data across treatment schools. Finally, the Performance Ready Leader Questionnaire revealed that school leaders mostly agreed that the Math Matters Program's resources, coaching, and professional development helped support the instructional practices within their schools. There were no significant variations in school leader perception across race or leader experience within the Math Matters Program. [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.]