Historically, STEM-related courses, specifically mathematics, have been looked at as a heavily White male and Asian-denominated space. The academic achievement gap seen with Black and Brown minorities within all content areas of public education is drastically large in the area of mathematics. Though the gap has shrunk, the number of minority students taking upper-level mathematics courses has not increased as the academic gap closes. Students' ability to thrive and successfully complete advanced-level content is highly correlated to their chances of completing post-secondary education. The lack of diversity within advanced academics translates to the need for more diversity in STEM-related jobs and careers. This study examines teacher perspectives of culturally relevant teaching to improve the enrollment and achievement of African American and Hispanic students in upper-level mathematics courses through its implementation. This study utilized a mixed-methods research approach, gathering data from questionnaires, one-on-one interviews, student enrollment numbers, and student course achievement scores. The results of this study reveal that while teachers understand the importance of implementing culturally relevant teaching practices, there must be teacher preparation programs that inform teachers of how this should look within mathematics and to what extent it should play a factor in their daily instruction and procedures. Research results also revealed that the enrollment practices do not but should allow teacher input or recommendations for student pathways toward graduation. Implementing practices that enable the teachers to provide student guidance based on their demonstrated mastery and classroom behaviors can counteract the lack of self-efficacy seen with minority students in non-minority-dominated spaces. [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.]