Teacher education programs can be perceived as a series of interventions with the goal of modifying, shifting, or constructing beliefs about teaching and learning. This means teacher education programs are in the business of identity development. Understanding the formation of prospective teachers' identities may better inform teacher educators in developing interventions used in teacher education programs. In this study I examined four prospective elementary teachers emotional geographies (Hargreaves, 2000) and constructed feeling rules (Hochschild, 1979) using the narratives of becoming a teacher shared during a practicum experience. The exploration of their emotional geographies provided a manifestation of their identity as mathematics teachers. The participants were prospective elementary teachers in their second semester of a two-year teacher education program. Each participant was interviewed three times throughout the semester. Additionally, the participants met as a group four times. All the interviews and small group meetings were transcribed. I analyzed the data using the emotional geographies framework for initial coding and an open coding process (Strauss & Corbin, 1990) within the geographies. After multiple rounds of coding, I identified themes and characteristics for the participants' emotional geographies. Additionally, the prospective teachers went through three stages of identity formation: (a) Peripheral participation (b) Seeking validation from students and authorities, and (c) Identity construction through reflection. The findings of this study demonstrate the powerful influence emotionality has on the identity formation as mathematics teachers of prospective teachers. I call for research in the overlap between emotions, teacher education, and identity formation to better understand the act of becoming and design stronger interventions for prospective teachers.