This qualitative study investigates the processes by which science and math teachers in high-need, urban schools develop a sense of professional identity, agency, and group membership in the context of instructional reform. Focusing on the experiences of two teachers, the paper explores both obstacles and affordances that teachers encounter when attempting to alter their instruction as part of school-wide initiatives to increase use of inquiry and cooperative learning. Findings included the potential for self-talk to contribute to an internal solidarity that can foster the maintenance of positive teacher identities in spite of challenges that emerge when implementing new lessons. However, teacher self-talk was partly shaped by the schools' procedures related to reform implementation. The results suggest that school approaches that promote teacher autonomy accompanied by support may help to center self-talk on motivational planning, which can increase confidence, sense of belonging, and reform-minded identities. In contrast, scripted and regimented approaches to reform may detach teachers from their sense of agency in the classroom, contributing to self-blame and disidentification with the instructional practices. Overall, the results of this study support the ways in which self-talk can be a mediating factor between structure, agency, and identity for early career teachers developing their practices, enabling them to make sense of their conditions and construct possibilities for action within them.