The aims of the study reported in this article are to investigate factors affecting English as a foreign language (EFL) teachers' use of computers in their classrooms and to find out EFL teachers' perceptions of computer-assisted language learning (CALL) and ways to improve CALL practice in school settings. Participants in the study were twelve Korean in-service teachers of EFL working at secondary schools in Korea. A questionnaire and follow-up in-depth interviews were employed to collect data. The results of the study indicate that the teachers have positive and favourable attitudes toward the use of the computers. They consider computer technology as a useful teaching tool that can enhance ways of teaching by offering students a variety of language inputs and expanding students' learning experiences in real and authentic contexts. It is also reported that external factors such as lack of time, insufficient computer facilities, rigid school curricula and textbooks and lack of administrative support negatively influence the implementation of CALL in the classroom. Internal factors such as teachers' limited computer skills, knowledge about computers and beliefs and perceptions of CALL also seem to significantly affect teachers' decisions on the use of CALL. Based on the findings of the study, implications are made for the effective implementation of CALL in EFL contexts.