In April 2012, junior high school education in Japan began to be conducted based on the revised course of study produced by the central government. In the section on ‘general policies regarding curriculum formulation,' teachers are expected to foster in students ‘a zest for life' through educational activities. In particular, teachers should be committed to fostering students' ability ‘to think', ‘to make decisions', and ‘to express themselves'. English teachers are expected to think about fostering learners' language skills to think logically and express their ideas and feelings effectively in the target language. The author argues that, initially, students need to understand and be aware of coherence in English passages and conversations. In order to contribute to this, a diagnostic test for evaluating learners' discourse competence in English, especially in relation to coherence, was developed and given to 498 junior high school students. The results of the survey indicated that the students lacked understanding in some areas of discourse competence. To remedy this, instruction and teaching materials should be more oriented towards making students aware of coherence in discourse, and they should be given more exercises or activities to develop their logical thinking and to express their ideas coherently in class.