SUMMARY
Inspired by the previous recast literature, this paper aims to investigate whether more explicit recasts are more effective than implicit recasts in second language grammar teaching and learning. Four empirical studies (two classroom-based and two laboratory-based) on implicit and explicit recasts were reviewed. In the two classroom-based studies, recasts were coded as explicit or implicit according to their length, intonation, number of changes, type of change, prosodic emphasis, etc. The effectiveness of recasts was measured by learners’ successful uptake rate and test scores. Conclusion drawn from these two studies is that more explicit recasts (e.g., short, declarative, reduced, one-change) tend to be more effective than implicit recasts in facilitating second language learning. In the two laboratory-based studies, recasts were divided as explicit or implicit mainly according to their intonation and the number of recast moves. Testing instruments included a spontaneous production test, an oral imitation test, and an untimed grammatically judgement test in one study; and an immediate and delayed error identification and correction tasks in the other study. Test scores and error correction rate were collected to measure the effectiveness of different recasts. Results suggest that, in laboratory settings, more explicit recasts might be more effective than implicit recasts or as effective as implicit recasts in grammar teaching and learning.