Building middle leading practice through pedagogy-focused professional development

School middle leaders (MLs) play a pivotal role in improving student outcomes through leading teaching and learning. However, MLs face considerable challenges in driving school improvement, including comparatively few opportunities for targeted professional development (PD). In this paper, we explore the impact of a pedagogy-focused, collaborative approach to PD, known as Quality Teaching Rounds (QTR), for middle leading practice. Twenty-two post-QTR interviews with MLs, principals and classroom teachers at nine primary schools in NSW, Australia, were thematically analysed using Kemmis's theory of practice architectures. We found that QTR positively impacted middle leading by: (1) building agreement about good pedagogical practice; (2) enhancing pedagogy through a process of reciprocal lesson observation; and (3) building collegial culture by flattening power hierarchies. We argue that it is critical to offer MLs powerful forms of collaborative PD if they are to enact the transformative potential of their role in driving pedagogical improvement.