This study examines elements of leading cooperative professional development (CPD) at different levels of the educational system to support national curriculum reform. While both the tri-level nature of leading large-scale reforms and the significance of teacher learning to support them are widely recognised, we lack understanding of how professional development is led in educational systems to support reform implementation. Abductive qualitative content analysis with a systemic tri-level approach was used to study elements of leading CPD activities at regional, local and school levels. The data consisted of nationwide questionnaires and semi-structured interviews for local and regional CPD coordinators in the Finnish Tutor teacher programme, a national CPD programme aiming to support large-scale curriculum reform. The findings indicate a significant and complex role of leading reform-related CPD at different levels of the educational system. Academic, instrumental and social elements of leading CPD were found to have specific approaches at regional, local and school levels. To our knowledge, this is the first study to examine the phenomenon at several levels of the education system. This systemic approach contributes to the scientific field as well as policy and practice by offering a better understanding of leading CPD to support reform implementation.