Low levels of literacy and numeracy skills are associated with a range of negative outcomes later in life, such as reduced employment, earnings and health. This review examines the effects of a broad range of school-based interventions targeting students with, or at risk of, academic difficulties on standardised tests in reading and maths. Included interventions changed instructional methods by, for example, using peer-assisted learning, introducing financial incentives, giving instruction in small groups, providing more progress monitoring, using computer-assisted instruction (CAI) and giving teachers access to subject-specific coaching. Some interventions targeted specific domains in reading and maths, such as reading comprehension, fluency and algebra, while others focused on building for example meta-cognitive and social-emotional skills. This review analyses evidence from 71 studies, 52 of which are randomised controlled trials.