This longitudinal collective case study is about the transformational experiences of three novice elementary teachers, Tammy, Katie, and Michelle, as they moved from an elementary teacher preparation program, at a large research university in the southeast United States, through their first two years of teaching in different elementary school contexts. Situated within literature pertaining to instructional vision and visions of high-quality mathematics instruction (VHQMI), these cases were used to explore the teachers' perceptions of their visions of high-quality mathematics instruction and how these perceptions evolve over time. The study design prioritizes novice teacher voices as predominant data sources to elevate their contribution to understanding their experiences within the mathematics education community. Learning from teachers how to best support teachers might inform teacher preparation programs, mathematics teacher educators, Pre-kindergarten-twelfth grade (P-12) schools and teachers working with teacher candidates or novice teachers, and other educational stakeholders. Assertions from this qualitative study point to the importance of developing VHQMI with teacher candidates in teacher preparation programs and with novice teachers through continued professional development and support from colleagues. By understanding how teachers evolve their instructional visions, we can develop more effective mathematics teacher education programs. We can reimagine partnerships between universities and P-12 schools where teachers engage in networking opportunities and have access to expert teaching practices and research. This could increase their desire to stay in the classroom long-term, which could stabilize teacher turnover and thus, advance the equity of access to high quality mathematics education for ALL students. [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.]