This brief summarises a rigorous literature review examining the quality and range of the measurement tools that are used to assess literacy and foundation learning in developing countries. The brief starts with background information including the theory underpinning the review and an outline of what assessments are used for. It then explores two issues that cut across all foundational learning assessments: the importance of context and problems with how results are reported. The main literacy assessments are then summarized, one sub-skill at a time. Factors that should be considered whenever assessing each sub-skill are identified. A short section outlining the main gaps in evidence is followed by a table showing how the main assessment instruments have performed.