This paper demonstrates the findings of an investigation into Korean secondary school English teachers’ practices and perceptions regarding writing instruction. The research employs in-depth interviews with a small number of teachers to identify: (a) teachers’ practices of writing instruction and assessment in the classroom; (b) teachers’ perceptions of writing instruction; (c) teachers’ evaluation of students’ writing abilities; and (d) teachers’ concerns or problems in teaching of writing. The results indicate that there exist discrepancies among teachers’ practices, perceptions, the National Curriculum and the College Scholastic Ability Test (CSAT): the curriculum provides writing goals that are too high for students; teachers cannot help focusing on low-level features of writing mainly due to students’ poor writing ability; and teachers and students do not have an urgent necessity to teach and learn writing, since writing is not tested in the CSAT. The paper concludes by providing implications and suggestions for future development of writing instruction in the Korean secondary school English classroom.