The ongoing focus on dispositions demonstrates the need for teacher educators to help preservice teachers develop from self-as-student to self-as-teacher. Our qualitative study examined preservice teachers' perceptions as they transitioned from university students to teaching professionals in a field experience program prior to student teaching. Main findings of preservice teachers' perceptions about their transition reflected three interrelated themes that link their professional growth to their dispositions and teacher self: (a) nascent understanding, (b) professional capacity, and (c) emergent identity. Within these three themes, attributes of the performance self, relational self, and professional self are described to support the relationship to dispositions and teacher identity. Teacher educators' understanding of preservice teachers' thinking during the field experience component of their preparation can inform faculty how to better structure and orchestrate learning experiences that will best contribute to the development of their emerging competence, professionalism, and teacher identities.