Purpose: The purpose of the study was to evaluate the implementation and impact of the IDEA Public Schools' Mathematics Curriculum Redesign (MCR) effort, funded by an Innovation and Research (EIR) grant. Methods: The study used a quasi-experimental matching design to examine the effect of MCR on student achievement outcomes. The study compared outcomes between the two cohorts of students at IDEA Public Schools that piloted the MCR and matched cohorts of students in IDEA schools that had delayed implementation of MCR. Results:?The study found statistically significant differences in IDEA Geometry test scores (ES = 0.39) between treatment and comparison group students in Grade 9 and on AP Calculus exam scores between treatment and comparison group students in Grade 12 (ES = 0.57). The study also found that the MCR program met the evaluation threshold for fidelity of implementation for the two out of three key program components (development of redesigned math curriculum and teacher use of math curriculum) in some years. The program did not meet the evaluation threshold for fidelity of implementation for the third key program components (teacher training and professional development to use redesigned math curriculum) in any of the years. Implications:?Because curriculum development and implementation are ongoing and iterative, realizing all of the benefits is not immediate and may take more time to achieve desired results. Continuous improvement of the curriculum and consistent supports to teachers will contribute to continued benefits for teachers and students while moving toward reaching anticipated student outcomes.