Purpose: This paper aims to explore developments over the past 25 years in the knowledge base on instruction-oriented middle leadership in schools. The authors document the trends in the literature since middle leadership began to attract scholarly interest in the late 1990s and explore the shifting structural and content patterns in the knowledge base. Design/methodology/approach: The authors use a topographic methodology to analyse both structural elements and major results drawing from 147 peer-reviewed journal articles. Findings: The authors draw on the review's outcomes to propose a model that frames a core set of middle leaders' instructional leadership practices. They also identify the personal, departmental, organizational and external influences shaping middle leadership practices and identify a lack of research conducted outside Anglo-American societies. This gap in the literature suggests the need for the increased study of middle leadership in different national settings and systems and how these influence the practice and enactment of middle leaders around instruction. There is also a need to employ a greater range of methodologies to understand middle leaders' instructional roles. Research limitations/implications The paper lays a foundation for the future development of middle leadership for instruction and highlights signposts to guide future inquiry. Originality/value: The paper contributes to the middle leader knowledge base by focussing on their enactment of instructional leadership.