This article reports on the results of a study which explored teachers transitioning from one year level to another in primary schools in New Zealand, and in particular the impact of this transition on teachers' professional identity. While this transition could be considered to be a commonplace occurrence in schools, the lack of literature indicates that it is currently under-researched. Findings from the study indicate that teachers can strengthen their professional identity as they experience positive outcomes in terms of their practice, pedagogy and relationships when they transition from one year level to another. However, attention is drawn to contextual factors which, if not fully understood and addressed, can lead to teachers having negative outcomes from transition. Finally, the important role that school leaders play to help alleviate these negative outcomes and ensure that teachers can successfully transition is also highlighted.