This article reviews research on oral corrective feedback (CF) in second language (L2) classrooms. Various types of oral CF are first identified, and the results of research revealing CF frequency across instructional contexts are presented. Research on CF preferences is then reviewed, revealing a tendency for learners to prefer receiving CF more than teachers feel they should provide it. Next, theoretical perspectives in support of CF are presented and some contentious issues addressed related to the role of learner uptake, the role of instruction, and the overall purpose of CF: to initiate the acquisition of new knowledge or to consolidate already acquired knowledge. A brief review of laboratory studies assessing the effects of recasts is then presented before we focus on classroom studies assessing the effects of different types of CF. Many variables mediate CF effectiveness: of these, we discuss linguistic targets and learners' age in terms of both previous and prospective research. Finally, CF provided by learners and the potential benefits of strategy training for strengthening the role of CF during peer interaction are highlighted.