Student success is an integral part of systemic change research. However, students' lived experiences and voices are often subdued in this programme, leaving the change that occurs to be evaluated upon measures that do not capture a holistic view of the experiences students and their shifting identities during the roll-out of those changes. These experiences could include not only the grades received and math course persistence, but also their perception of instructional practices, their attitudes towards mathematics, and their sense of belonging in math settings. In this dissertation, students' experiences and identities are investigated through a mixed-methods research design, with a critically inspired theoretical perspective of Figured Worlds interfaced with Critical Race Feminism. A survey that included Likert scale and free-response items was administered to students enrolled in Precalculus, Calculus I, and Calculus II. Additionally, semi-structured interviews with several students were conducted. Through qualitative analysis, students' meaning of mathematics and their personal mathematical narratives are constructed. Additionally, emergent themes of identity-based struggles contextualize the diverse population of individuals that make up the survey population. Instructional practices that mediate these identities and support diverse student needs are identified and discussed. Through quantitative analysis, I make the argument for expanding the conceptualization of student success from grades and course persistence to become more holistic by analyzing these traditional measures as well as novel affective measures that paint a broader picture of students' identities and experiences. This argument is based in a demonstration of analyzing these factors comparing responses to a survey from students enrolled in a newly designed support course and students who did not enroll in the support course. The results indicate that students in the support course overall were marginally more 'successful' than their peers in terms of grades received, positive shifts in confidence, and sense of belonging. These results suggest that not only is the support course we designed a viable option for supporting students, but also that systemic change research ought to consider students' voices, identities, and experiences when measuring student success. [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.]