This study explored the differences in student achievement on New York State standardized tests between blended learning and traditional instructional methodologies. Specifically, the study compared student achievement in iLearnNYC schools, to their peer schools that deliver instruction in a traditional manner. iLearnNYC is a blended learning program where online content complements in-class teaching and allows students more control over the pace in which they learn, where they learn, and what they learn. A quasi-experimental quantitative design was used to analyze test scores on the June 2014 and June 2015 administration of the New York State Common Core Algebra I exams (Appendix B & C) for both the blended learning and the traditional learning groups. Statistical analyses was performed on the data to determine the differences in students' mean scores, as well as differences in achievement levels for various sub-groups of the sample. The study found that students in the Blended Learning group (iLearnNYC schools) did not have statistically significant greater mean scores in overall performance on Common Core Algebra I Regents exam than their peers in the Traditional Learning group (peer schools). This study also found that Students with Disability (SWD's) in the traditional learning group significantly outperformed their counterparts in the blended learning group. Additionally, there was not a significant difference for English Language Learners (ELLS) between the blended learning and the traditional groups. This study concludes that other variables such as students' prior academic results, students' attendance, and teachers' experience should be considered if blended learning is to be used as a comprehensive school reform model to increase students' overall performance on state standardized math exams. Transitioning from a traditional to a blended model can produce many challenges. These challenges can relate primarily to faculty and learner time; level of effort; familiarity, skill, and comfort-level with online platform (Lotrecchiano et al., 2013). [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 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]