Meta-syntheses have reported positive impacts of feedback for student achievement at different stages of education and have been influential in establishing feedback as an effective strategy to support student learning. However, these syntheses combine studies of a variety of different feedback approaches, combine studies where feedback is one of a number of intervention components and have several methodological limitations (for example, the lack of quality appraisal of the included studies). There is also still more research needed to investigate the impact of different types of feedback on different students in different settings. This systematic review was conducted at the request of the Education Endowment Foundation to provide more precise estimates of the impact of different types of feedback in different contexts for different learners aged between 5 and 18. The review analysis sought to explore potential variations in the impact of feedback through subgroup analysis of the characteristics of the feedback, the educational setting, the learners and the subject. The results of the review may be considered broadly consistent with claims made on the basis of previous synthesis and meta-synthesis, suggesting that feedback interventions, on average, have a positive impact on attainment when compared to no feedback or usual practice. Findings were further interpreted by a panel of expert practitioners and academics to produce the Education Endowment Foundation's (EEF's) "Teacher Feedback to Improve Pupil Learning. Guidance Report" (ED615988).