Purpose: The purpose of this paper is to explore the role and leadership practices of executive leaders in English multi-academy trusts (MATs) considering the meaning of system-level leadership and its perceived impact on schools' improvement processes, conditions and culture. Design/methodology/approach: This paper was guided by an ecological systems approach emphasizing the interactions between the micro-, meso-, macro-, exo- and chronosystems, and was used to develop context-sensitive accounts of leadership across groups of schools. It involves interview-based multi-perspective case studies using a sample of five MATs and collecting data from 31 interviews with various school and MAT leaders. Findings: The primacy of leadership at the executive level was central to efforts for school and MAT transformation and that was evident throughout the findings of the study. System leadership was multifaceted and was understood through the multiple layers of the organizational structure of MATs. Four major domains of practice highlight the efforts of these leaders to address complex and systemic challenges. These are setting strategic directions, developing people and organizational capacity, establishing organizational infrastructure to support schools' improvement efforts and providing instructional guidance. Originality/value: Findings reveal new empirical data about the role of executive leaders in English MATs and highlight the ways in which they seek to establish, manage and sustain school and MAT-wide improvement providing the research with a holistic idea of system leadership.