Research on teacher identity has suggested that being able to envision oneself as a teacher of science is an important part of becoming a teacher of science. Identity is a multifaceted construct and for prospective elementary teachers there are many possible sources for learning about what it means to be a teacher and these sources may tell conflicting stories. The negotiation of these dissonant identity stories may in fact be a productive space for prospective teacher identity development. Using a narrated identity framework, I explored the identity of one prospective elementary teacher as a teacher of science. Additionally, I observed how she enacted this identity within the context of her student teaching. Findings from this case study showed that the prospective teacher tried to enact identity stories that had their roots in her science methods course, but at times was challenged by the identity stories that were told by her mentor teacher about what it meant to be a teacher of science. Encountering these conflicts required the prospective teacher to negotiate the dissonance identities as she enacted her identity as a teacher of science. These findings suggest that supporting prospective teachers in negotiating dissonant identities may be an important role for teacher educators.