In the current globalized world, English is an international language that makes it possible for people from different language backgrounds to communicate with each other. In this situation, English users in EIL (English as an international language) should be able to comprehend various accents spoken by English speakers from all over the world. Therefore, in order to investigate how to help Korean high school EFL (English as a foreign language) learners to develop their listening comprehension of various accents of English, this study conducted an experiment by having them listen to various accents of English. Participants were divided into an experimental group and a control group. The experimental group received a treatment of listening to various accents and solving listening comprehension questions. They did reading while listening activity with the same accents when checking their answers. On the other hand, the control group received the same treatment and did the reading while listening activity when checking their answers. The only difference between the groups was that the experimental group listened to various accents of English and the control group listened to American accents. After the treatment, both groups took two pretests. It was found through test score analyses that listening to various accents helped participants to develop their listening comprehension of the accents better than listening to American accents. Furthermore, participants in the experimental group could transfer their listening comprehension developed through the treatment to new contexts such as listening to English accents that they did not practice and listening to real-life listening materials. Along with test score analyses, it was found through a questionnaire that participants who received the treatment of listening to various accents of English perceive that they could transfer their developed listening comprehension. In addition, their responses showed that they recognize the importance of dealing with various accents for international communication and they think English classes in school should deal with various accents of English. With the results, this study insisted that CSAT (College Scholastic Ability Test) listening comprehension section should include various accents of English in order to help Korean high school EFL learners to prepare for international communication situations. With washback effects of CSAT, it will lead Korean EFL stakeholders to be able to prepare for English communications in EIL situations.