This article illustrates the role of teacher identity in teacher self-efficacy development during initial teacher education. It has been posited that teacher self-efficacy develops on the basis of information accessed through four self-efficacy sources: vicarious and enactive experiences, social persuasion, and physiological and affective states, and by interacting with a myriad of personal and external factors. The very process of teacher self-efficacy development, however, is not well understood. This phenomenological longitudinal qualitative case study contributes to addressing this issue by illustrating how a pre-service secondary mathematics teacher's teacher self-efficacy is affected by the way she sees herself. More specifically, the study illustrates how aspects of a strong student teacher identity negatively affect the pre-service teacher's teacher self-efficacy appraisal, and how her teacher identity, emerging through the processes of autonomous role enactment and social verification, supports teacher self-efficacy development.