This paper presents a summary of a three-year project funded by the Education Endowment Foundation (EEF) evaluating the Schools Partnership Programme (SPP). The SPP is a peer-led, collaborative school improvement model in England, developed by the Education Development Trust (EDT), where clusters of schools conduct peer reviews and support one another's improvement. The study was conducted by academics at the UCL Centre for Educational Leadership and involved both quantitative and qualitative methods, including a quasi-experimental impact evaluation and a mixed-methods process evaluation (Godfrey et al., 2023). This condensed report focuses on key findings and offers research-driven recommendations for policymakers and school leaders, specifically regarding how peer-led initiatives can foster teacher professional development (TPD), improve school outcomes, and encourage leadership. The theoretical underpinning is based on the Joint Practice Development (JPD) model, where learning is collaborative, practice based and deeply integrated into the fabric of school improvement (Sebba et al., 2012).