The present study aimed at investigating the effects of the two types of teacher feedback--direct corrective feedback (DCF) and metalinguistic explanation (ME)--on the development of EFL learners' knowledge of the English indefinite article and on their use of it in writing. For this study, 58 college students classified into three groups (two experimental groups and one control group) took the error correction test and performed three writing tasks. The results of the study are: (1) there was no group effect of the two types of feedback in the development of their explicit knowledge of the target feature in the test, whereas a time effect was found that their knowledge of the target feature developed significantly after the treatment; and (2) no group differences were found between the two types of feedback in the use of the target feature in the revised writing and among the three writings, though the DCF group outperformed the ME group in the accurate use of the target feature in writing. Theoretical and pedagogical relevance of the findings is addressed.