Although the concept of middle leadership has received some attention in the literature since the late 1990s, it continues to be under-researched and under-theorised. A shift in terminology from 'middle management' to 'middle leadership' over this time suggests that the roles of middle leaders in schools have been evolving. Middle leaders are becoming more important as links between the vision of senior leadership teams and the daily work of teachers at the 'chalkface'. However, without a conceptual point of reference it is difficult to examine how that evolution is occurring and identify implications for school effectiveness. This article presents a conceptual framework of middle leadership roles derived from relevant literature and suggests items that capture elements of those roles that could be used for future quantitative investigations. The article concludes with practical implications of their use for investigating middle leadership in schools and contributing to much needed theory building.