This pilot study aims to explore the effect of corrective feedback on learners' written productions by looking at two types of feedback on verb and preposition errors taking place on wikis. Corrective feedback types include recasts (reformulations of incorrect forms) and metalinguistic clues (explanations for linguistic errors). Thirteen English as a foreign language (EFL) learners participated in this study. They were randomly assigned into the three conditions, namely, recasts, metalinguistic clues, and no feedback. The preliminary results derived from the posttest writing suggest that those who received corrective feedback outperformed those who did not; the metalinguistic clues group had a greater number of correct targeted items than did the recast group. Furthermore, all participants of the three groups agreed that corrective feedback was necessary to enhance writing abilities in English. This study concludes with the pedagogical implications and suggestions for future studies.