This article reports on an increasing number of SLA studies showing that interactional feedback plays a significant role in improving classroom learners’ use of the target language. Whereas the provision of feedback has proven more effective than no feedback, there are still many variables that mediate the effectiveness of interactional feedback. This article synthesizes a set of classroom studies about interactional feedback taking into account four mediating variables: (a) feedback types, (b) instructional setting, (c) learners’ age, and (d) linguistic targets. The synthesis leads to the conclusion that prescriptions to use only “implicit negative feedback” at the expense of other more overt types of interactional feedback are not supported by classroom research. The article closes with a recommendation for teachers to adopt a wide variety of interactional feedback techniques in accordance with a range of contextual, individual, and linguistic variables.