Over decades, as researchers have proposed different views on error corrections, the effectiveness of oral corrective feedback (OCF) has still remained indeterminate. The present study synthesizes existing empirical OCF studies to examine the effectiveness of OCF on learner's L2 development. Further, several moderating effects which include learner characteristics, research design, and variables in OCF were involved in the study as well. A total of 41 primary studies published between 1988 and 2018 were collected, and 204 effect sizes were meta-analyzed. Results from random-effects models revealed a small-to-medium effect (g = 0.662) and established the presence of true heterogeneity (