Abstract
The present study was an attempt to explore how Iranian EFL learners use definite/indefinite articles. The researcher tried to find out whether Iranian EFL learners used the articles the same as native speakers do and also to found the frequency and the type of the errors made by Iranian EFL learners. To investigate the relationship between the proficiency of Iranian EFL learners and their using of definite/indefinite articles was another goal of the study. To achieve the purpose, 152 Iranian EFL graduate and undergraduate students were selected to participate in the study. The participants were the undergraduate TEFL students of Salman Farsi University of Kazerun and Persian Gulf University and the others were BA or MA graduate students of other universities. In the process of data collection, the students were told that they were participating in a research study and their identity would remain anonymous, only their level of proficiency would be used in the analysis. First, the OPT was used in order to determine the participants’ proficiency level. Then, the participants were asked to write well-organized essays whose topics were set in advance. They were asked to develop their arguments for and against the topics. The essays gathered were added to PerGULC, a corpus collected by Abbasi and Nemati (2011) in Persian Gulf University. At last, to analyze the collected data, the Stanford Tagger, AntConc software, and Pearson Product-moment correlation test were run to answer the study's research questions. The obtained results revealed that Iranian EFL student underuse articles in comparison to the English native speakers. Moreover, there was a significant correlation between students’ English proficiency scores and the number of articles they used in their compositions. At last, the researcher found that errors in the use of the definite article was the most common ones, and the most common error type in definite article use was the insertion of “the”. Based