Middle leaders and school improvement work in light of principal turnover

Principal turnover is known for contributing to decreased student performance, increased teacher mobility, and disrupted school improvement work. However, the linking mechanisms remain insufficiently understood, especially beyond statistical analysis, making it difficult for practitioners to address these issues. This study contributes to a deeper contextual understanding of principal turnover and its impact on schools’ middle leaders and their school improvement work. The study uses semi-structured interviews with middle leaders and principals from two Swedish schools with different principal turnover rates. The interviews are analysed using cultural–historical activity theory. The finding suggests that principal continuity fosters an expanding middle-leadership role, contributing to coherent school improvement work, whereas principal discontinuity generates multiple ideas of middle leadership but prevents deeper development, contributing to repeated restarts regarding school improvement work. A long-term relationship between principals and middle leaders appears to be a prerequisite for effective and sustainable school improvement work. This study highlights the need for robust support structures that enable principals to remain in their positions long enough to build sustainable distributed leadership and for middle leaders to maintain consistency in school improvement work despite principal turnover. Additionally, policy measures must address the structural conditions contributing to high leadership turnover.