The purpose of this study is to better understand teacher professional development in a paired-placement context. It focuses specifically on how two teacher students (STs) in Vietnam, Hien and Chinh, develop their professional identities in the collaborative setting, and how factors specific to pair-work mediate this process. Findings from this study suggest that an individual teacher’s identity influences her/his cognitive and affective perception of an event. Paired-placement created an environment whereby the student teachers’ conflicting identities, associated with different cognitive and affective perceptions of the experience, were challenged, leading to contradictions. However, within the framework of planned and supervised collaboration, the STs resolved most of their conflicts constructively and experienced qualitative development in their teaching identities.