This longitudinal narrative inquiry explores the influences on a first-year elementary teacher's mathematics-related teacher identity, employing a community of practice lens. Identity is a complex concept. In this study, identity is viewed as socially constructed through new experiences. These social interactions can be seen as an individual participates in their communities of practice. A mathematics-related teacher identity intertwines a teacher's mathematical identity with their teacher identity. This can influence their classroom decisions, as well as their planning and implementation of mathematics lessons. To gain insights into the evolution of this mathematics-related teacher identity, I listened to the stories of Suzie, a first-year teacher, as she engaged with three distinct communities of practice: parent community, classroom community, and grade team community. My goal was to understand how the communities influenced her mathematics-related teacher identity. Suzie and I cultivated a research friend relationship, fostering trust and care throughout the study. This unique relationship allowed me gain a deeper understanding of Suzie's experiences. Throughout the school year, Suzie and I convened ten times to discuss her journey, supplemented by her monthly self-reflections. Employing a narrative approach, I made sense of Suzie's experiences through the storying and re-storying pivotal moments from her first year of teaching. I examined the stories both holistically and took a closer look at micro-moments. The findings from this study capture the interconnectedness of experiences within and between an individual's communities of practice. Suzie's stories illuminate the contributions confidence and communication in shaping a teacher's mathematics-related teacher identity. Based on these findings, I created a new model to illustrate the construction of a mathematics-related teacher identity within communities of practice. Indicating the benefit of additional research on the effect of communication within a teacher's communities of practice and a teacher's confidence. An implication from this study, revealing the dynamic interplay between a teacher's communities of practice, is that teacher preparation and induction programs may need to reconsider the extent to which they prepare novice teachers to actively participate in and attend to these multiple Communities of 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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]