This study explores the efficacy of the Math Workshop Model in enhancing the capacity of secondary mathematics teachers to differentiate instruction, implement equitable teaching practices, and meet the diverse needs of students in mixed-ability classrooms. Through a mixed methods approach, including classroom observations, interviews, and surveys conducted within a large public school district in New Jersey, this research examines how structured activities, formative assessments, small group instruction, and flexible, strategic, collaborative student groupings within the Math Workshop Model contribute to a dynamic, inclusive, and engaging learning environment. The findings reveal significant improvements in teachers' ability to provide differentiated instruction and maintain high expectations for all students, fostering an equitable classroom atmosphere. Challenges related to classroom management and the integration of the model at the high school level underscore the need for ongoing professional development. This study contributes to the field by highlighting the Math Workshop Model's potential to transform secondary mathematics education, suggesting further research on its long term impact on student achievement and the optimization of teacher training programs. [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://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]