Implementation is making, and acting on, evidence-informed decisions. Yet awareness of evidence does not necessarily result in improved outcomes: implementation is critical for turning engagement with research into tangible changes in school practices and pupil outcomes, including, crucially, for pupils experiencing socio-economic disadvantage. Nevertheless, changing the established habits and behaviours of educators through implementation isn't straightforward. On the one hand, schools need to develop a practical infrastructure that supports implementation, such as sufficient time and resources; on the other, implementation is fundamentally a social process, and getting the interactions right between people across the school is essential. This guidance helps schools embrace the complex and social nature of change. A theme across this guidance report is that evidence and data should inform all aspects of implementation, both what to implement and how. Effective implementation requires ongoing learning and adaptation informed by different types of evidence, including external research evidence and internal monitoring data.