In the most challenging educational contexts, some schools outperform others despite similar contexts and levels of resources. How do these schools achieve improved outcomes? Data Must Speak (DMS), a global initiative to address evidence gaps to mitigate the learning crisis, provides evidence on what works, why, and how to scale grassroots solutions. This methodological review presents key definitions, concepts, and methodologies of approaches (e.g. positive deviance, behavioural sciences, implementation research) to guide and inform the development and implementation of the DMS research at the country level, in addition to examples of best practices and lessons learned from these approaches.