• meta-analysis;
  • corrective feedback;
  • recasts;
  • metalinguistic feedback;
  • implicit feedback;
  • explicit feedback;
  • moderator variables

This study reports on a meta-analysis on the effectiveness of corrective feedback in second language acquisition. By establishing a different set of inclusion/exclusion criteria than previous meta-analyses and performing a series of methodological moves, it is intended to be an update and complement to previous meta-analyses. Altogether 33 primary studies were retrieved, including 22 published studies and 11 Ph.D. dissertations. These studies were coded for 17 substantive and methodological features, 14 of which were identified as independent and moderator variables. It was found that (a) there was a medium overall effect for corrective feedback and the effect was maintained over time, (b) the effect of implicit feedback was better maintained than that of explicit feedback, (c) published studies did not show larger effects than dissertations, (d) lab-based studies showed a larger effect than classroom-based studies, (e) shorter treatments generated a larger effect size than longer treatments, and (f) studies conducted in foreign language contexts produced larger effect sizes than those in second language contexts. Possible explanations for the results were sought through data cross-tabulation and with reference to the theoretical constructs of SLA.