Supporting pre-service teachers to develop equity-oriented beliefs and practices is often a goal of teacher preparation. However, there is a need for greater understanding of how the development of content-specific equity-oriented beliefs and practices may be supported or hindered during student teaching experiences. This study aims to explore the beliefs and understandings student teachers hold about equitable mathematics teaching and how these beliefs and understandings may be influenced during student teaching. In particular, I focus on how the beliefs and practices of mentor teachers may influence the ways in which student teachers conceptualize equitable mathematics teaching. To do this, I developed and distributed a survey prior to and at the completion of student teaching placements to both elementary student teachers and their mentors. I also engaged in three cycles of journal reflections and semi-structured interviews with four pairs of student teachers and mentor teachers across three months during the student teaching placements. My findings indicate that these student teachers and mentor teachers reported different emphases in their beliefs about and conceptualizations of equitable mathematics teaching. During the student teaching placement, the student teachers reported to grow in the ways in which they operationalized equitable mathematics teaching and their understandings of equitable mathematics teaching became more grounded in the practices of their mentors. In these ways, the student teachers' understandings of how to enact equitable mathematics teaching grew in the areas in which their mentor teachers conceptualized equity, but remained stagnant in the areas that did not align with their mentors' conceptualizations. Additionally, both mentor teachers and student teachers highlighted the influence of critical reflections in supporting them to consider how they promote equity in their teaching of mathematics. These findings contribute to the field by showing ways in which student teachers' understandings of equitable mathematics teaching may be deepened or constrained by the beliefs and practices of their mentors. They also highlight possible avenues through which teacher educators may support both in-service and pre-service teachers in developing knowledge and skills in enacting equitable mathematics teaching in their practice. [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/en-US/products/dissertations/individuals.shtml.]