The present study explores the effect of providing different types of written corrective feedback (WCF) on 79 Iranian EFL learners’ writings over time through a pre-test, immediate post-test and delayed post-test. In this way, the study first aims to investigate the extent to which different types of WCF result in improved accuracy in writing over a period of two months, and then maintains to see if there is a differential effect on accuracy when the students are required to revise their writings based on the feedback provided to them over this period. However, to narrow down the scope of the study, considering the level of the learners, and the type and complexity level of the expected writing tasks, it was decided to use the three linguistic errors (capitalization errors, the correct use of definite and indefinite articles, and simple present tense verb) which occurred mostly frequently during the participants' first writing tasks as the target linguistic structures of the work. After analyzing the collected data, it was found that providing WCF indeed contributes to the accuracy of the students’ writings because the results indicated each type of feedback employed in the treatment groups could clearly bring about writing improvement at varying degrees. In particular, the findings suggested that direct feedback might bring about greater effects on students’ writing accuracy, whereas different types of feedback are more likely to produce rather long term improvement and/or learning over time.
