This study examines the transformation and dynamic nature of one teacher candidate's (Susan) identity as a learner and teacher of science throughout an innovative science methods course. The goal of this paper is to use theoretically derived themes grounded in cultural-historical activity theory (CHAT) and situated learning theory to determine the ways in which Susan's identity as a learner and teacher of science was influenced by her experiences in the course, and to describe how she made meaning of her transformative process. The following are the three theoretical themes: (1) learning contributes to identity development, (2) identity development is a dialogical process that occurs between individuals, not within individuals, and (3) social practice leads to transformations and transformations lead to the creation of new social practices. Within each theme, specific experiences in the science methods course are identified that influenced Susan's identity development as a teacher of science. Knowing how context and experiences influence identity development can inform design decisions concerning teacher education programs, courses, and experiences for candidates.