Lesson study is a collaborative model of professional development that provides teachers with the opportunity to learn from the planning, conduction and reflection of a specifically designed research lesson. Lesson study is increasingly incorporated in initial teacher education (ITE) and calls have been made to further detail the lesson study structures that support student teacher learning. In this paper the core organisational elements of incorporating lesson study in ITE are investigated as a comparative case study situated in two distinct educational and cultural settings: one in Ireland (post-primary) and the other in Norway (primary). Qualitative data, including student teachers' planning notes, research lesson designs, and observation notes from live research lessons, were analysed and findings reveal three structural factors for the incorporation of lesson study in ITE. First, defined roles of mentor and university teachers as knowledgeable others; second, the engagement of student teachers at each phase of lesson study, with the inclusion of case pupils; and third, the conduction of the lesson study cycle on both university campus and in the classroom. These findings contribute to the growing literature of lesson study in ITE and may support the inclusion of lesson study in ITE programmes.