The purpose of this multiple case study was to follow the development of three music educators during their student teaching semesters and into the first years of their careers. Possible selves theory provided a framework for exploring the links between cognition, expectations, and motivation. Interviewees negotiated their social and physical contexts, which in turn shaped their self-images and conceptions of teaching and learning. Identities were constructed through personal experiences and formal study with significant others, including influential teachers, cooperating teachers, and colleagues. In these respects, classrooms served as the laboratories in which teachers learned how to build crucial relationships with their students, tested and reshaped emerging identities, and based actions and evaluation on their possible selves.