This mixed methods study explores high school seniors' math course-taking decisions and what changes school leaders can take to increase the percentages of students taking four years of math in high school. Through an analysis of district-level administrative data and a survey completed by seniors at a high performing, diverse high school in Northern California, this study illuminates many reasons for why these patterns and inequalities occur. Findings reveal institutional, classroom and individual factors that impact students' decision-making around taking math senior year. [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.]