||Kim, Nayu & Lee, Heechul. (2018). A study on the definite article in English based on the Rasch model. The Linguistic Association of Korea Journal, 26(4), 37-54. The purpose of this study is to investigate the hierarchy of difficulty in the usage of the definite article by high school students in Korea based on the Rasch model and to analyze what causes the hierarchy of difficulty. This study investigates 133 high school students' responses on eight different uses of the definite article as noted by Segall (1990). According to the findings, it is confirmed that students respond differently to the definite article depending on whether they have grammatical knowledge of it and understand the context of paragraphs. In order for students to understand the definite article correctly, systematic lessons are needed in English reading and writing classes. Moreover, an English teacher should include sentences that have different meaning by the definite article distributed throughout the text when designing a lesson plan for reading comprehension.