This article presents a case study of a unique New Zealand professional development programme, Te Kotahitanga, for mainstream secondary school teachers. Findings discussed are drawn from an independent evaluation of the programme across 22 secondary schools. The professional development approach attempted to reposition the relationship between teachers and Indigenous Maori students, and enhance Maori student outcomes. Interviews with 150 teachers across participating schools investigated teacher perceptions of impact on classroom practice and student outcomes across subjects. The professional development programme was associated with shifts in teachers' understandings of their positioning within classrooms and relationships with and expectations for Maori students. Results also highlight ongoing challenges in teachers' repositioning and the development of new relationship-based approaches. The implications for teaching practice and professional learning programmes and recommendations for further research are discussed.