The purpose of this study was to investigate how three Chinese teachers developed their teacher identities in a reform context. Drawing upon data from a larger social historical study, the work-life narratives of the three teachers at different stages of their careers were used as case studies to showcase three types of teacher identity development trajectories, namely, learning to be both professional educator and subject teaching expert, learning to be subject teaching expert, and navigating to balance between educator and subject teacher. This study also investigated the factors that influence identity development trajectories of teachers and develops a conceptual framework for understanding teacher identity development in China. The framework shows that Chinese teachers' exertion of their individual agency is embedded in the institutional context. Meanwhile, interpersonal relationships can work as a buffer to alleviate the tension between the institution and individual teachers. The study also shows the ways in which Chinese teachers' exert their agency when developing their identities. The findings have significant implications for teacher education in terms of how to develop positive teacher identity over the course of a teacher's career.