In this article, we use a narrative methodology to understand the work of three teachers who have constituted identities that have allowed them to challenge the contemporary discourse of science education. We describe how teachers' evolving identities have been constituted through their responses to the discourses and situations of their work and their emotional response to these experiences. A Foucauldian analysis of the data indicates three important conclusions. The first is the need for, or development of, an environment that immerses teachers in discourse that allows, and actively supports, classroom practices that challenge the contemporary discourse. A key component of such discourse is an awareness of the emotional aspects of teaching. The second conclusion is the potential power of the mandated curriculum to legitimize, for teachers, discourses that challenge the contemporary discourse. Third, individual teachers may lack the power necessary to establish discourse environments that fully capitalize on their potential influence within the infrastructure of pedagogical science.